A single-ion conductor star-shaped block copolymer and a preparation method and application thereof

Abstract

The application discloses a single-ion conductor star-shaped block copolymer and a preparation method and application thereof. The method comprises the following steps: reacting potassium phosphate, 1-butyl mercaptan and carbon disulfide at 25-30 DEG C while stirring, then adding 1,3,5-tris(bromomethyl)benzene and reacting at 25-30 DEG C while stirring for 10-12 hours, separating and drying the product in the reaction solution to obtain intermediate I, reacting methoxy polyethylene glycol acrylate and the intermediate I under the action of an initiator at 75-85 DEG C in a vacuum state for 45-50 hours, separating the product in the reaction solution to obtain intermediate II, reacting lithium ethylene bisphenylsulfonylimide and the intermediate II under the action of an initiator at 75-85 DEG C in a vacuum state for 45-50 hours, and separating the product in the reaction solution to obtain the single-ion conductor star-shaped block copolymer. The single-ion conductor star-shaped block copolymer is used as a filler to solve the problem of low ion conductivity of a solid-state polymer electrolyte.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid electrolyte preparation, in particular to a single-ion conductor star block copolymer and a preparation method and application thereof. BACKGROUND

[0002] Since the advent of lithium metal batteries (LMBs) in the last century, they have achieved wide application and development prospects from portable mobile electronic devices such as mobile phones and computers to electric vehicles and smart grids due to their high energy storage and safety performance. However, the active metal lithium anode is prone to react with traditional liquid electrolytes, and uncontrolled lithium dendrites grow continuously. The final result can penetrate the separator and cause the battery to short circuit. In addition, the organic liquid electrolyte is prone to combustion, leakage and thermal instability, and can even cause a battery disaster of fire or explosion. Therefore, it has been widely recognized that replacing the unsafe organic liquid electrolyte with a safer solid-state electrolyte (SSE) is the development trend of lithium metal batteries.

[0003] As a major type of solid-state electrolyte, solid-state polymer electrolytes (SPEs) have unique mechanical properties. Due to their advantages such as good flexibility, light weight, good processability, and low cost, they have become one of the most promising key battery materials that can replace flammable organic liquid electrolytes. The characteristic structure (-CH2-CH2-O-) contained in polyethylene oxide (PEO) n allows it to complex with many lithium salts, so PEO is a suitable host material for SPEs. However, PEO-based composite solid-state electrolytes are difficult to simultaneously have high mechanical strength and room-temperature ionic conductivity.

[0004] Dispersing inert inorganic fillers such as SiO2, Al2O3, TiO2, LiAlO2, and ZrO2 nanoparticles in SPEs can increase the room-temperature ionic conductivity of SPEs by 1-2 orders of magnitude, from 10 -7 to 10 -5 S cm -1 However, this method of directly adding inorganic particles to solid-state polymer electrolytes cannot directly participate in ion conduction and is also prone to agglomeration, thus limiting the wide application of lithium ion batteries. SUMMARY

[0005] In view of the problems in the prior art, the present application provides a single-ion conductor star block copolymer and a preparation method and application thereof, which can promote lithium ion conduction and inhibit PEO crystallization. The single-ion conductor star block copolymer as a filler solves the problem of low ionic conductivity of solid-state polymer electrolytes.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A process for the preparation of a single-ion conductor star block copolymer comprising the steps of:

[0008] Step 1: reacting tri-potassium phosphate, 1-butyl mercaptan and carbon disulfide in a substance amount ratio of 1:1:3 at 25-30°C under stirring, then adding 1,3,5-tris(bromomethyl)benzene and reacting at 25-30°C under stirring for 10-12 hours, the substance amount ratio of carbon disulfide and 1,3,5-tris(bromomethyl)benzene being 10.5:1, and finally separating and drying the product in the obtained reaction solution to obtain intermediate I;

[0009] Step 2: reacting methoxy polyethylene glycol acrylate and intermediate I in a substance amount ratio of (33-34):(1-2) under the action of an initiator at 75-85°C for 45-50 hours in a vacuum state, separating the product in the obtained reaction solution to obtain intermediate II;

[0010] Step 3: reacting lithium ethylene bisbenzenesulfonylimide and intermediate II in a substance amount ratio of (9-10):3 under the action of an initiator at 75-85°C for 45-50 hours in a vacuum state, separating the product in the obtained reaction solution to obtain the single-ion conductor star block copolymer.

[0011] Preferably, in Step 1, tri-potassium phosphate, 1-butyl mercaptan, carbon disulfide and acetone are mixed uniformly at a temperature of -5 to 0°C, the substance amount ratio of carbon disulfide and acetone being 3:29, then stirring for 1-1.5 hours, reacting at 25-30°C under stirring for 10-12 hours, placing the obtained mixed solution in an environment of -5 to 0°C, then adding 1,3,5-tris(bromomethyl)benzene and stirring for 1-1.5 hours, and then reacting at 25-30°C under stirring.

[0012] Preferably, in Step 1, the obtained reaction solution is first rotary evaporated, then the obtained solid is dissolved in dichloromethane, washed with deionized water using a separatory funnel, the lower solution is dried with MgSO4, then filtered with a sand core funnel, the obtained filtrate is rotary evaporated to obtain intermediate I.

[0013] Preferably, the initiator in Step 2 and Step 3 is both azobisisobutyronitrile, wherein the substance amount ratio of methoxy polyethylene glycol acrylate and azobisisobutyronitrile in Step 2 is (33-34):1, and the substance amount ratio of lithium ethylene bisbenzenesulfonylimide and azobisisobutyronitrile in Step 3 is (9-10):4.

[0014] Further, in step 2, methoxy polyethylene glycol acrylate, azobisisobutyronitrile and intermediate I are dissolved in ethyl acetate, with the ratio of ethyl acetate to methoxy polyethylene glycol acrylate being (13-17) ml: 12.5 mmol, and then reacted under vacuum.

[0015] Preferably, in step 2, the obtained reaction solution is quenched in water at 2-5°C to obtain a mixed system, and the mixed system is rotary evaporated at 35-40°C for 20-30 minutes to obtain intermediate II.

[0016] Preferably, in step 2, lithium vinylbisbenzenesulfonylimide, azobisisobutyronitrile and intermediate II are dissolved in methanol, with the ratio of methanol to lithium vinylbisbenzenesulfonylimide being (13-17) ml: 6.07 mmol, and then the reaction is carried out under vacuum.

[0017] Preferably, in step 3, the obtained reaction solution is quenched in water at 2-5°C, and then rotary evaporated at 35-40°C for 15-20 minutes to obtain a single-ion conductor star-shaped block copolymer.

[0018] A single-ion conductor star-shaped block copolymer obtained by the preparation method of any one of the above-described single-ion conductor star-shaped block copolymers.

[0019] Application of single-ion conductor star-shaped block copolymers in the preparation of polyoxyethylene composite solid electrolytes.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a method for preparing a single-ion conductor star-shaped block copolymer. Tripotassium phosphate, 1-butanethiol disulfide, and 1,3,5-tris(bromomethyl)benzene undergo a substitution reaction. The copolymer is first reacted with methoxy polyethylene glycol acrylate using reversible addition-fragmentation chain transfer polymerization under the action of an initiator, and then reacted with the lithium-ion monomer lithium vinylbisbenzenesulfonylimide under the action of an initiator. The resulting star-shaped block copolymer, as a filler, can regulate the intermolecular interaction between PEO and lithium salt. The polar groups in PEGMA and LiSSPSI exhibit different conduction effects on lithium ions depending on whether they are located at the proximal or distal end, thus inhibiting PEO crystallization and improving the overall performance of the composite solid electrolyte as a thin film.

[0022] Using the star-shaped block copolymer obtained in this invention as an organic filler, and with PEO / lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the matrix, a polyoxyethylene composite solid electrolyte was prepared and assembled into a lithium-ion battery. This battery exhibited the highest ionic conductivity (0.063 mS / cm) at 60°C. -1 ), the largest t Li+(0.81) and a relatively wide electrochemical stability window (4.72V). After being assembled into a lithium iron phosphate full cell, it maintains good cycle performance after long-term charge-discharge. Attached Figure Description

[0023] Figure 1 The NMR spectrum of intermediate I obtained in Example 1 of this invention is shown.

[0024] Figure 2 The NMR spectrum of intermediate II obtained in Example 1 of this invention is shown.

[0025] Figure 3 The NMR spectrum of the single-ion conductor star-shaped block copolymer obtained in Example 1 of this invention is shown. Detailed Implementation

[0026] To enable those skilled in the art to better understand the solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] This invention discloses a method for preparing a single-ion conductor star-shaped block copolymer, comprising the following steps:

[0028] Step 1: At -5 to 0°C, mix tripotassium phosphate, 1-butanethiol, carbon disulfide, and acetone in a molar ratio of 1:1:3:39, using acetone as the solvent. Stir for 1-1.5 hours to obtain mixture a. Then, transfer mixture a to 25-30°C and continue stirring for 10-12 hours to obtain mixture b. Place mixture b at -5 to 0°C and add an acetone solution of 1,3,5-tris(bromomethyl)benzene in a molar ratio of 7:2 (1-butanethiol:1,3,5-tris(bromomethyl)benzene). The amount of acetone added should be sufficient to dissolve the 1,3,5-tris(bromomethyl)benzene. For ease of operation, in subsequent examples, the amount of acetone used here is 34 times that of 1,3,5-tris(bromomethyl)benzene. Stir for 1-1.5 hours, then transfer the resulting mixture a to 25-30°C and continue stirring for 10-12 hours. Acetone was removed by rotary evaporation (35-40℃, 15-20 min). The resulting solid was then dissolved in 100 mL of dichloromethane (DCM). The solid was washed three times with 100 mL of deionized water using a separatory funnel. The lower layers were combined and dried with MgSO4. The solid was then filtered through a sintered glass funnel and rotary evaporated (25-35℃, 5-10 min) to obtain intermediate I. The reaction formula is as follows.

[0029] All of the above stirring methods are beneficial to the reaction and improve the conversion rate.

[0030]

[0031] Step 2: Add methoxy polyethylene glycol acrylate (PEGMA, degree of polymerization n 7-9, readily available), azobisisobutyronitrile (AIB), and intermediate I to the reactor and dissolve them in ethyl acetate. The molar ratio of PEGMA:AIB:Intermediate I is (33-34):1:(1-2), and the ratio of ethyl acetate to PEGMA is 13-17 ml:12.5 mmol. Evacuate the reactor to a vacuum and react at 75-85°C for 45-50 h. Quench the reactor in ice water at 2-5°C to stop the polymerization reaction, resulting in mixture b. Rotary evaporate mixture b at 35-40°C for 20-30 min to remove the solvent ethyl acetate, yielding intermediate II. The reaction formula is as follows, where m = 173-188.

[0032]

[0033] Step 3: Lithium-ion monomers lithium vinylbis(benzenesulfonyl)imide (LiSSPSI), azobisisobutyronitrile (AIBN), and intermediate II are added to the reactor and dissolved in methanol. The molar ratio of LiSSPSI:AIBN:intermediate II is (9-10):4:3, and the ratio of methanol to LiSSPSI is 13-17 ml:6.07 mmol. The reactor is evacuated to a vacuum and reacted at 75-85°C for 45-50 h. The polymerization reaction is stopped by quenching the reactor in ice water at 2-5°C, yielding mixture c. Mixture c is then rotary evaporated (35-40°C, 15-20 min) to remove the solvent, yielding a single-ion conductor star-shaped block copolymer. The reaction formula is as follows, where y = 28-30.

[0034]

[0035] The single-ion conductor star-shaped block copolymer of the present invention can be used to prepare polyethylene oxide (PEO) based composite solid electrolytes.

[0036] A single-ion conductor star-shaped block copolymer was used as a filler and added to a PEO solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at mass ratios of 10%, 20%, and 30% based on PEO (the molar ratio of [PEO] to lithium bis(trifluoromethanesulfonyl)imide = 20). The mixture was stirred for 22-26 hours. PEO served as both a solvent and a matrix material. The solution was poured into a mold, and the PEO solution solidified to form a film, thus obtaining a composite solid electrolyte. The film was then dried in a vacuum oven at 60-70°C for 45-50 hours to remove the solvent, polyethylene oxide. The resulting film was then cut into discs with a diameter of 18-20 mm and stored in a glove box.

[0037] Example 1

[0038] A method for preparing a single-ion conductor star-shaped block copolymer, the method comprising the following steps:

[0039] Step 1: K3PO4 (14.9 g, 0.07 mol), acetone (150 mL), and 1-butanethiol (6.31 g, 7.6 mL, 0.07 mol) were added sequentially to a two-necked flask. The mixture was stirred at 0 °C. An acetone solution of CS2 was added dropwise, with 12.6 mL (0.21 mol) of CS2 and 50 mL (0.68 mol) of acetone. Therefore, the total volume of acetone in the system was 200 mL, and the total amount of substance was 2.72 mol. The mixture was stirred at 0 °C for 1 h, followed by stirring at room temperature for 12 h. The resulting reaction mixture was then stirred at 0 °C. An acetone solution of 1,3,5-tris(bromomethyl)benzene was added dropwise, with 7.14 g (0.02 mol) of 1,3,5-tris(bromomethyl)benzene and 50 mL of acetone. The mixture was stirred at 0 °C for 1 h, followed by stirring at room temperature for 12 h. The solvent was removed by rotary evaporation (40℃, 15 min). The resulting solid was then dissolved in 100 mL of dichloromethane (DCM). The solid was washed three times with 100 mL of deionized water using a separatory funnel. The lower layer solutions were combined and dried with MgSO4. The solid was filtered through a sintered glass funnel and the filtrate was then rotary evaporated (30℃, 10 min) to obtain intermediate I.

[0040] Step 2: PEGMA (6.0 g, 12.5 mmol), azobisisobutyronitrile (AIBN) (62 mg, 0.37 mmol), and intermediate I (360 mg, 0.59 mmol) were dissolved in 15 mL of ethyl acetate in a 100 mL Schlenk flask. After degassing via three freeze-thaw cycles, polymerization was carried out at 80 °C for 48 h. Polymerization was stopped by quenching the reaction mixture in ice water at 3 °C. The resulting mixture was then rotary evaporated at 38 °C for 25 min to remove the solvent, yielding intermediate II.

[0041] Step 3: LiSSPSI (2 g, 6.07 mmol), azobisisobutyronitrile (AIBN) (40 mg, 0.24 mmol), and intermediate II (2 g, 0.18 mmol) were dissolved in 15 mL of methanol in a 100 mL Schlenk flask. After degassing through three freeze-thaw cycles, polymerization was carried out at 80 °C for 48 h. The polymerization was stopped by quenching the reaction solution in ice water at 3 °C, and the resulting mixture was rotary evaporated (37 °C, 18 min) to remove the solvent, yielding a single-ion conductor star-shaped block copolymer.

[0042] Figure 1 , Figure 2 and Figure 3The images show the 1H NMR spectra of intermediates I, II, and the single-ion conductor star-shaped block copolymer, respectively. Figure 1 The results show that the two peaks at chemical shifts of 1.5 ppm and 5.3 ppm belong to the solvent peaks of residual water and dichloromethane during purification, the peak at 7.25 ppm can be attributed to the only hydrogen on the benzene ring, and the peaks at 4.5 ppm, 3.4 ppm, 1.5 ppm and 1.0 ppm can be attributed to the saturated hydrogen on the aliphatic chain connected to the benzene ring, which proves that intermediate I was successfully synthesized. Figure 2 The data shows that the 6.5-6.0 ppm range represents a weak vinyl absorption peak on the PEGMA monomer, confirming the successful synthesis of intermediate II. From... Figure 3 The short and broad peaks at chemical shifts of 7.4–7.9 ppm and 0.7–2.0 ppm are attributed to the transformation of benzene ring units on the monomer LiSSPSI into saturated methylene units after polymerization of vinyl groups. Therefore, the single-ion conductor star-shaped block copolymer was successfully synthesized.

[0043] This invention relates to the application of a single-ion conductor star-shaped block copolymer for preparing a PEO-based composite solid electrolyte. Specifically, the single-ion conductor star-shaped block copolymer PLi-(PPM-T) obtained in Example 1 is added to a PEO solution in LiTFSI at a mass ratio of 10% based on PEO (the molar ratio of [PEO] to lithium bis(trifluoromethanesulfonylimide) = 20). After stirring for 24 hours, the solution is poured into a mold using a solution casting method. The PEO solution solidifies to form a film, thus obtaining the composite solid electrolyte. The film is then dried in a vacuum oven at 60°C for 48 hours to remove the solvent. The removed film is then cut into discs with a diameter of 19 mm and stored in a glove box.

[0044] Example 2

[0045] A method for preparing a single-ion conductor star-shaped block copolymer, the method comprising the following steps:

[0046] Step 1: K3PO4 (14.9 g, 0.07 mol), acetone (150 mL), and 1-butanethiol (6.31 g, 7.6 mL, 0.07 mol) were added sequentially to a two-necked flask. The mixture was stirred at 0 °C, and CS2 (12.6 mL, 0.21 mol) in acetone (50 mL) was added dropwise. The mixture was stirred at 0 °C for 1 h, followed by stirring at room temperature for 12 h. The reaction was then carried out below 0 °C with stirring, and 1,3,5-tris(bromomethyl)benzene (7.14 g, 0.02 mol) in acetone (50 mL) was added dropwise. The mixture was stirred at 0 °C for 1 h, and then stirred at room temperature for 12 h. The solvent was removed by rotary evaporation (35℃, 20 min), and then dissolved in 100 mL of DCM. The solution was washed three times with 100 mL of water using a separatory funnel. The lower layer was dried with MgSO4, filtered through a sintered funnel, and the filtrate was obtained by rotary evaporation (35℃, 5 min) to obtain intermediate I.

[0047] Step 2: PEGMA (6.0 g, 12.5 mmol), azobisisobutyronitrile (AIBN) (62 mg, 0.37 mmol), and intermediate I (360 mg, 0.59 mmol) were dissolved in 15 mL of ethyl acetate in a 100 mL Schlenk flask. After three freeze-thaw cycles for degassing, polymerization was carried out at 80 °C for 48 h. Polymerization was stopped by quenching the polymer solution in ice water at 4 °C. The solvent was removed by rotary evaporation at 37 °C for 26 min to obtain intermediate II.

[0048] Step 3: LiSSPSI (2 g, 6.07 mmol), azobisisobutyronitrile (AIBN) (40 mg, 0.24 mmol), and intermediate II (2 g, 0.18 mmol) were dissolved in 15 mL of methanol in a 100 mL Schlenk flask. After degassing through three freeze-thaw cycles, polymerization was carried out at 80 °C for 48 h. Polymerization was stopped by quenching the polymer solution in ice water at 2 °C. The solvent was removed by rotary evaporation of the mixture (36 °C, 17 min) to obtain a single-ion conductor star-shaped block copolymer.

[0049] An application of a single-ion conductor star-shaped block copolymer for preparing a PEO-based composite solid electrolyte is described. The single-ion conductor star-shaped block copolymer PLi-(PPM-T) obtained in Example 2 is added to a PEO solution in LiTFSI at a mass ratio of 20% based on PEO (the molar ratio of [PEO] to lithium bis(trifluoromethanesulfonylimide) = 20). After stirring for 24 hours, the solution is poured into a mold using a solution casting method. The PEO solution solidifies to form a film, thus obtaining the composite solid electrolyte. The film is then dried in a vacuum oven at 60°C for 48 hours to remove the solvent. The film is then cut into discs with a diameter of 19 mm and stored in a glove box.

[0050] Example 3

[0051] A method for preparing a single-ion conductor star-shaped block copolymer, the method comprising the following steps:

[0052] Step 1: K3PO4 (14.9 g, 0.07 mol), acetone (150 mL), and 1-butanethiol (6.31 g, 7.6 mL, 0.07 mol) were added sequentially to a two-necked flask. The mixture was stirred at -3°C, and CS2 (12.6 mL, 0.21 mol) in acetone (50 mL) was added dropwise. The mixture was stirred at 0°C for 1 h, followed by stirring at room temperature for 12 h. The reaction was then stirred below 0°C, and 1,3,5-tris(bromomethyl)benzene (7.14 g, 0.02 mol) in acetone (50 mL) was added dropwise. The mixture was stirred at 0°C for 1 h, and then stirred at room temperature for 12 h. The solvent was removed by rotary evaporation (37℃, 18 min), and then dissolved in 100 mL of DCM. The solution was washed three times with 100 mL of water using a separatory funnel. The lower layer was dried with MgSO4, filtered through a sintered funnel, and the filtrate was obtained by rotary evaporation (25℃, 10 min) to obtain intermediate I.

[0053] Step 2: PEGMA (6.0 g, 12.5 mmol), azobisisobutyronitrile (AIBN) (62 mg, 0.37 mmol), and intermediate I (360 mg, 0.59 mmol) were dissolved in 15 mL of ethyl acetate in a 100 mL Schlenk flask. After three freeze-thaw cycles for degassing, polymerization was carried out at 80 °C for 48 h. Polymerization was stopped by quenching the polymer solution in ice water at 2 °C. The solvent was removed by rotary evaporation at 39 °C for 25 min to obtain intermediate II.

[0054] Step 3: LiSSPSI (2 g, 6.07 mmol), azobisisobutyronitrile (AIBN) (40 mg, 0.24 mmol), and intermediate II (2 g, 0.18 mmol) were dissolved in 15 mL of methanol in a 100 mL Schlenk flask. After degassing via three freeze-thaw cycles, polymerization was carried out at 80 °C for 48 h. Polymerization was stopped by quenching the polymer solution in ice water at 4 °C. The solvent was removed by rotary evaporation of the mixture (40 °C, 15 min) to obtain a single-ion conductor star-shaped block copolymer.

[0055] An application of a single-ion conductor star-shaped block copolymer for preparing a PEO-based composite solid electrolyte is described. The single-ion conductor star-shaped block copolymer PLi-(PPM-T) obtained in Example 3 is added to a PEO solution in LiTFSI at a mass ratio of 30% based on PEO (the molar ratio of [PEO] to lithium bis(trifluoromethanesulfonylimide) = 20). After stirring for 24 hours, the solution is poured into a mold using a solution casting method. After the PEO solution solidifies, a film is formed to obtain the composite solid electrolyte. The film is then dried in a vacuum oven at 60°C for 48 hours to remove the solvent. The film is then cut into discs with a diameter of 19 mm and stored in a glove box.

[0056] The thin films obtained in the above three embodiments (denoted as PLi(PPM)-CSE-x, where x is the mass fraction of PLi-(PPM-T) in PEO) were packed into batteries in a glove box to obtain lithium-ion batteries. The method assembled a Li / PLi(PPM)-CSE-x / Li symmetric battery. PLi(PPM)-CSE-x was sandwiched between two lithium metal electrodes. The ionic conductivity and lithium-ion transference number were tested, and the results are shown in Table 1.

[0057] Table 1

[0058] 25 °C ionic conductivity (S / cm) 60 °C ionic conductivity (S / cm) Lithium ion transference number Example 1 1.46 x 10 -4 ]]> 5.08 x 10 -4 ]] 0.66 Example 2 2.03 x 10 -4 ]] 5.08 x 10 -4 ]]> 0.77 Example 3 2.71 x 10 -4 ]] 6.35 x 10 -4 ]]> 0.81

[0059] Ion conductivity (σ) is a key indicator for evaluating the performance of a battery. It is measured through AC impedance testing, based on... The ionic conductivity was calculated.

[0060] Lithium-ion transference number (t) Li+ The lithium-ion transference number (LTN) is a parameter used to evaluate ion mobility. The LTN is measured using the potentiostatic polarization method with an applied voltage of 10 mV. Li+ The following equation is used for calculation, where all parameters are known, so their meanings will not be explained further:

[0061]

[0062] In the formula

[0063] I0 — Initial current (μA)

[0064] I ss —Steady-state current (μA)

[0065] ΔV — is the applied voltage (mV)

[0066] R0 — Initial resistance (Ω)

[0067] R ss —Steady-state resistance (Ω)

[0068] The data in the table show that the lithium-ion battery made using the single-ion conductor star-shaped block copolymer provided by this invention exhibits excellent electrochemical performance. Specifically, the single-ion conductor star-shaped block copolymer electrolyte filler obtained in Examples 1-3 has an ionic conductivity of 1.46–2.71 × 10⁻⁶ at 25°C. -4 S / cm, ionic conductivity at 60℃ is 5.08~6.35×10 -4 S / cm, lithium-ion transport number t Li+ The value ranges from 0.66 to 0.81.

[0069] Furthermore, measurements using linear sweep voltammetry showed that the lithium-ion batteries assembled from the thin-film PLi(PPM)-CSE-x obtained in the three examples all exhibited electrochemical stability windows greater than 4.72V. Typically, PEO-based composite solid electrolytes oxidize at approximately 4.2V, but all PLi(PPM)-CSE-x batteries remained stable up to 4.2V. A larger electrochemical stability window indicates greater battery stability and suitability for high-voltage applications.

[0070] Comparing Examples 1 to 3, it can be found that the higher the amount of single-ion conductor star-shaped block copolymer added, the better the battery performance.

[0071] Table 2

[0072] Specific capacity / mAh g -1 ]] Coulombic efficiency Before cycling 158 98％ After cycling 156 98％

[0073] Table 2 presents the analysis data of constant current charge-discharge after assembling the single-ion conductor star-shaped block copolymer PLi-(PPM-T) obtained in Example 3 into a lithium iron phosphate full cell (LFP|PLi(PPM)-CSE-30|Li). The changes in specific capacity and coulombic efficiency of the battery after 100 cycles at a rate of 0.2C are compared. Therefore, it can be shown that the lithium iron phosphate full cell can maintain good cycle performance after long-term charge-discharge.

Claims

1. A method for preparing a single-ion conductor star-shaped block copolymer, characterized in that, Includes the following steps: Step 1: Tripotassium phosphate, 1-butanethiol, and carbon disulfide were reacted at 25-30 °C with stirring in a molar ratio of 1:1:

3. Then, 1,3,5-tris(bromomethyl)benzene was added and the mixture was reacted at 25-30 °C with stirring for 10-12 h. The molar ratio of carbon disulfide to 1,3,5-tris(bromomethyl)benzene was 10.5:

1. Finally, the product in the resulting reaction solution was separated and dried to obtain intermediate I. Step 2: According to the molar ratio of (33-34): (1-2), methoxy polyethylene glycol acrylate and intermediate I are reacted in vacuum at 75-85 °C for 45-50 h under the action of an initiator. The products in the resulting reaction solution are separated to obtain intermediate II. Step 3: In a molar ratio of (9-10):3, lithium vinylbisbenzenesulfonylimide and intermediate II are reacted under vacuum at 75-85 °C for 45-50 h with an initiator. The product in the resulting reaction solution is separated to obtain a single-ion conductor star-shaped block copolymer.

2. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, Step 1: First, mix tripotassium phosphate, 1-butanethiol, carbon disulfide, and acetone evenly at a temperature of -5 to 0 ℃, with a molar ratio of carbon disulfide to acetone of 3:

29. Then stir for 1-1.5 h and react with stirring at 25-30 ℃ for 10-12 h. Place the resulting mixture in an environment of -5 to 0 ℃, then add 1,3,5-tris(bromomethyl)benzene and stir for 1-1.5 h. After that, react with stirring at 25-30 ℃.

3. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, Step 1: First, the obtained reaction solution is evaporated by rotary evaporation. Then, the obtained solid is dissolved in dichloromethane, washed with deionized water using a separatory funnel, the lower layer solution is dried with MgSO4, filtered with a sintered glass funnel, and the filtrate is rotary evaporated to obtain intermediate I.

4. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, The initiators mentioned in steps 2 and 3 are both azobisisobutyronitrile, wherein the molar ratio of methoxy polyethylene glycol acrylate to azobisisobutyronitrile in step 2 is (33-34):1, and the molar ratio of lithium vinylbisbenzenesulfonylimide to azobisisobutyronitrile in step 3 is (9-10):

4.

5. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 4, characterized in that, Step 2: Dissolve methoxy polyethylene glycol acrylate, azobisisobutyronitrile and intermediate I in ethyl acetate, with the ratio of ethyl acetate to methoxy polyethylene glycol acrylate being (13-17) ml: 12.5 mmol, and then react under vacuum.

6. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, Step 2: Quench the obtained reaction solution in water at 2-5 °C to obtain a mixed system. Then, rotary evaporate the mixed system at 35-40 °C for 20-30 min to obtain intermediate II.

7. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, Step 2: Lithium vinylbis(benzenesulfonyl)imide, azobisisobutyronitrile and intermediate II are dissolved in methanol in a ratio of (13-17) ml: 6.07 mmol, and then reacted under vacuum.

8. The method for preparing the single-ion conductor star-shaped block copolymer according to claim 1, characterized in that, Step 3 involves quenching the resulting reaction solution in water at 2-5 °C, followed by rotary evaporation at 35-40 °C for 15-20 min to obtain a single-ion conductor star-shaped block copolymer.

9. A single-ion conductor star-shaped block copolymer obtained by the preparation method of any one of claims 1-8.

10. The application of the single-ion conductor star-shaped block copolymer as described in claim 9 in the preparation of polyoxyethylene composite solid electrolyte.

Images