An ionic conductive polymer silicon anode binder with molecular pulley function and its preparation method

Abstract

The present invention provides an ionic conductive polymer silicon negative electrode binder with a molecular pulley effect, a preparation method thereof, and an application thereof. The binder has a high ionic conductivity, and through the structural design combining the molecular pulley effect, excellent comprehensive performance of the silicon negative electrode is achieved. The silicon negative electrode sheet obtained by coating a nano-silicon negative electrode slurry configured based on such a binder has characteristics such as a high first-cycle Coulomb efficiency, a low electrode impedance, and a high capacity retention rate.

Description

Technical Field

[0001] The present invention belongs to the technical fields of new materials for lithium batteries and polymer technology, and particularly relates to an ion-conducting polymer silicon anode binder with a molecular pulley effect, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries have been widely used due to their advantages such as high energy density, high working voltage, and no memory effect. With the substantial growth of the markets for lithium-ion power batteries and energy storage batteries, the market has put forward higher requirements for the energy density of lithium batteries. At the level of anode materials, currently about 99% of batteries use graphite as the anode, but the theoretical specific capacity of graphite is only 372 mAh g -1 . With the optimization of graphite preparation and electrode coating processes, the actual specific capacity of high-end graphite anodes has been able to reach over 360 mAh g -1 , approaching its theoretical value infinitely, and it is difficult to achieve a breakthrough in the energy density of the full battery. As an anode material, the theoretical specific capacity of crystalline silicon is 4200 mAh g -1 , which is much higher than that of graphite currently used on a large scale in commerce, and is expected to become the next-generation anode material for high-energy-density lithium batteries. However, the initial Coulombic efficiency (ICE) of silicon electrodes is low, and the volume change rate after reacting with lithium ions to form an alloy is >300%. During the cycling process, the electrodes are prone to fragmentation, pulverization, and even detachment from the current collector. The newly exposed silicon surface in the electrolyte will repeatedly form a solid electrolyte interphase (SEI), and the battery capacity will decay significantly with the increase in the number of cycles.

[0003] Current research improves the comprehensive performance of silicon anodes through methods such as nanostructure design of silicon materials, preparation of silicon composites, preparation of artificial SEI films, and prelithiation. However, these methods are complex in process and high in cost, and it is difficult to promote their application on a large scale (Nature Nanotechnology, 2008, 3(1): 31-35; Nano Energy, 2020, 72: 104657; Energy Storage Materials, 2020, 29: 190-197). Solving the problems faced by silicon anodes through the preparation of high-performance binders can directly match the current electrode coating process in the battery manufacturing industry and has greater potential for industrialization.

[0004] In recent years, various types of binders have been reported to address the issues of rapid capacity decay and low initial Coulombic efficiency in silicon anodes, including binders based on hydrogen bonding, ion pair interactions, self-healing binders, dynamic cross-linking binders, and conductive binders. The design and application of functional binders can effectively improve the performance of silicon-based anodes (ChemSusChem, 2020, 13(15): 3887-3892; Advanced Energy Materials, 2015, 5(8): 1401826; Nano Energy, 2020, 67: 104234). However, there are few reports on ion-conductive binders with high ionic conductivity. In addition, studies have shown that polyrotaxanes exhibit excellent performance in different anodes such as crystalline silicon, silicon monoxide, and silicon-carbon composites. The molecular dynamic interaction can enhance the adaptability of silicon-based anodes to volume changes during charge and discharge processes, significantly improving the battery cycle performance (Advanced Materials, 2019, 31(51): e1905048; Advanced Energy Materials, 2022, 12(11): 2103718). Therefore, the design of a new binder with high ion conductivity and a molecular pulley dynamic cross-linking structure is expected to achieve excellent comprehensive performance of silicon anodes. Summary of the Invention

[0005] In view of the above problems in the prior art, the present invention provides an ion-conductive polymer with a molecular pulley effect that can be used as a binder for silicon anodes. The ion-conductive polymer has the following structure:

[0006]

[0007] Wherein,

[0008] a bond or hydrogen connected to R, provided that not all are hydrogen, m1 = 90 - 100, m2 = 10 - 20, preferably 14 - 18, k = 2 - 20; preferably, in each unit, bond = 0.5:1 to 2:1;

[0009] R j In R

[0010] wherein, R1 is selected from:

[0011] R2 is a polymer group that is not reactive to isocyanates. The polymer group contains one or more aliphatic, alicyclic, and / or aromatic groups and has a number average molecular weight of 1000 - 4000. Preferably:

[0012] Among them, n1 = 10 - 40, n2 = 6 - 24

[0013] R3 is selected from: In the formula, n = 15 - 20, preferably 18.

[0014] The present invention further provides a method for preparing the ion-conductive polymer, characterized in that the method comprises the following steps:

[0015] Step 1: Catalytically react a polymer polyol, a diisocyanate, and a lithium salt of a bis-hydroxy-terminated sulfonimide polymer in a solvent to obtain a sulfonimide-type prepolymer;

[0016] The polymer polyol is a polyol formed by a polymerization group that is non-reactive to isocyanate and a hydroxyl group. The polymerization group contains one or more aliphatic, alicyclic, and / or aromatic groups. The polymer polyol has a number-average molecular weight of 1000 - 4000, preferably a polymer diol, and most preferably one or a mixture of polytetrahydrofuran and polycarbonate diol.

[0017] The diisocyanate is selected from one or more of 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0018] The lithium salt of the bis-hydroxy-terminated sulfonimide polymer has

[0019] the structure of;

[0020] The structural general formula of the sulfonimide-type prepolymer is shown as follows:

[0021]

[0022] In the formula, R1 is selected from:

[0023] R2 is a polymerization group that is non-reactive to isocyanate. The polymerization group contains one or more aliphatic, alicyclic, and / or aromatic groups and has a number-average molecular weight of 1000 - 4000, preferably: In the formula, n1 = 10 - 40, n2 = 6 - 24;

[0024] R3 is selected from: In the formula, n = 15 - 20, preferably 18;

[0025] Step 2: Catalytically react the sulfonimide-type prepolymer prepared in Step 1 with a polyrotaxane in a solvent to obtain an ion-conductive polymer;

[0026] The polyrotaxane has the following structure:

[0027]

[0028] Wherein: Wherein m1 = 90 - 100, m2 = 10 - 20, preferably 14 - 18. Preferably, in each unit, H = 0.5:1 to 2:1.

[0029] The lithium salt of the dihydroxy - terminated sulfonimide polymer is prepared by reacting the MR3' salt with the compound of formula (a) and LiOH,

[0030] Wherein, the compound of formula (a) is Where n = 18;

[0031] M is an amine cation, preferably a tertiary amine cation, most preferably a triethylamine cation;

[0032] R3' is selected from

[0033] Preferably, both Step 1 and Step 2 are carried out in an anhydrous and anaerobic environment;

[0034] Preferably, the catalyst in Step 1 and Step 2 is selected from tin compounds such as tin diacetate, tin dioctoate, tin dilaurate, or a mixture of one or more of dialkyl derivatives of dialkyltin salts of aliphatic carboxylic acids such as stannous octoate, dibutyltin diacetate or dibutyldilauryltin;

[0035] Preferably, the mass ratio of the polymer polyol, the lithium salt of the dihydroxy - terminated sulfonimide polymer and the diisocyanate is 0.1:0.1:1 to 4:4:1;

[0036] Preferably, the catalyst content accounts for 0.1% - 1% of the total feed mass;

[0037] Preferably, the polyrotaxane accounts for 5% - 35% of the mass of the prepolymer;

[0038] Preferably, the polymer polyol is selected from one or a mixture of polytetrahydrofuran with a number - average molecular weight of 1000, 2000 or 4000, and polycarbonate diol with a number - average molecular weight of 1000, 2000 or 4000.

[0039] Preferably, the solvent is selected from one or a mixture of dimethyl sulfoxide, N,N - dimethylformamide, and N - methylpyrrolidone.

[0040] The present invention further provides a silicon anode binder material, which comprises the above - mentioned ion - conductive polymer.

[0041] The technical problem to be solved by this application is to provide a preparation method of an ion-conducting polymer silicon anode binder material with a molecular pulley effect, which has the characteristics of easily available raw materials, controllable process, mild conditions, etc., can be used for large-scale industrial production, and has good practicability. Another technical problem to be solved by the present invention is to provide an application of an ion-conducting polymer silicon anode binder material with a molecular pulley effect in the field of silicon anode slurries. Configuring a nano-silicon anode slurry based on such a binder has the characteristics of simple method, uniform slurry, mild conditions, etc., can be used for large-scale industrial production, and has good practicability. Another technical problem to be solved by the present invention is to provide an application of an ion-conducting polymer silicon anode binder material with a molecular pulley effect in the field of lithium-ion batteries. The silicon anode sheet obtained by coating a nano-silicon anode slurry configured based on such a binder has the characteristics of high first-cycle Coulomb efficiency, low electrode impedance, high capacity retention rate, etc., and has very good application prospects in the field of lithium-ion batteries, greatly improving the battery energy density. Description of the Drawings

[0042] Figure 1 It is a cyclic charge and discharge test data graph of the silicon electrode sheets corresponding to Example 3 and Comparative Example 1 at a current density of 0.1C.

[0043] Figure 2 It is the AC impedance spectrum of the silicon electrode sheets corresponding to Example 3 and Comparative Example 1 before cycling.

[0044] Figure 3 It is the AC impedance spectrum of the silicon electrode sheets corresponding to Example 3 and Comparative Example 1 after cycling.

[0045] Figure 4 It is the scanning electron microscope image of the silicon electrode sheets corresponding to Example 3 and Comparative Example 1.

[0046] Figure 5 It is the infrared spectrum of the ion-conducting polymer silicon anode binder material corresponding to Example 1. Detailed Embodiments

[0047] Example 1

[0048] This example provides an ion-conducting polymer silicon anode binder solution with a molecular pulley effect.

[0049] The specific steps are as follows:

[0050] 1. Synthesis of lithium trifluoromethanesulfonimide polymer salt (P-T-Li)

[0051]

[0052] Synthesis of poly(epoxy bromopropane) (PEBH):

[0053] Under argon protection, 0.9 g (6 mmol) of boron trifluoride etherate and 0.375 g (6 mmol) of ethylene glycol were added to a 100 ml three-necked flask, and the mixture was stirred at room temperature for 1 h. Subsequently, the reaction system was evacuated to remove ether, completing the preparation of the cationic initiator. 20 ml of anhydrous dichloromethane was added for dilution, and the system was transferred to an ice-water bath. 42.6 g (310 mmol) of epibromohydrin (EBH) was added dropwise evenly within 4 h using a constant-flow automatic sampler for ring-opening polymerization. After the addition was completed, the mixture was stirred at room temperature for another 1 h, and the polymerization reaction was terminated using 20 ml of saturated sodium bicarbonate solution. The organic phase of the mixture was washed twice with 20 ml of saturated sodium bicarbonate solution and then twice with 20 ml of deionized water. After washing, the organic phase was dried using anhydrous sodium sulfate, and dichloromethane (DCM) was removed by rotary evaporation and vacuum-dried to obtain a colorless viscous liquid product PEBH (38.9 g, ~284 mmol-Br), with a yield of 90.2%. The product can be directly used in subsequent reactions without further treatment.

[0054] Synthesis of PEBH-ET:

[0055] 38.9 g (~284 mmol-Br) of PEBH obtained in the previous step and 35.6 g (312 mmol) of potassium thioacetate were added to a 250 ml eggplant-shaped flask, and 100 ml of acetone was added and refluxed for 14 h. After the reaction was completed, acetone was removed by rotary evaporation, 100 ml of DCM was added to dissolve the product, and solid salt impurities were removed by filtration. After removing DCM by rotary evaporation and vacuum-drying, a yellow viscous liquid product PEBH-ET (34.1 g, ~258 mmol-SC(O)CH3) was obtained, with a yield of 90.9%. The product can be directly used in subsequent reactions without further treatment. Synthesis of dihydroxy-terminated side-mercapto oligomer (PEBH-SH):

[0056] 34.1 g (~258 mmol-SC(O)CH3) of PEBH-ET obtained in the previous step and 100 ml of 5 M MeONa / MeOH solution were added to a 500 ml eggplant-shaped flask and diluted with 50 ml of methanol. The resulting orange-red solution was stirred at 50 °C for 2 h. After the reaction was completed, methanol was removed by rotary evaporation. The resulting mixture was dissolved in 250 ml of deionized water and the pH was adjusted to 3 - 4 using 25 wt% sulfuric acid in an ice-water bath. When the pH was adjusted to acidic, the orange-red polymer precipitated from the solution. The product was dissolved in 100 ml of DCM and dried using anhydrous sodium sulfate. After removing DCM by rotary evaporation and vacuum-drying, an orange-red viscous liquid product PEBH-SH (21.6 g, ~250 mmol-SH) was obtained, with a yield of 92.9%. The product can be directly used in the preparation of subsequent single-ion oligomers without further treatment.

[0057]

[0058] Synthesis of 4bz-SO2Cl:

[0059] First, perform an anhydrous and anaerobic treatment on a 250 ml three-necked flask. Subsequently, add 29.4 g of sodium p-styrenesulfonate (4bz), 120 ml of HPLC-grade DMF, and transfer the system to an ice-water bath. Dropwise add 44 ml of thionyl chloride within 30 min using a constant-pressure dropping funnel. After dropping, transfer it to 60 °C for reaction for 2 h. After the reaction is completed, drop the reaction mixture into ~250 g of ice water, extract it twice with 80 - 100 ml of diethyl ether, dry it with anhydrous sodium sulfate, and then rotary evaporate to obtain a brown liquid product (~24 After removing diethyl ether by rotary evaporation, an orange-yellow liquid product p-styrenesulfonyl chloride (4bz-SO2Cl, 26.1 g, 129 mmol) can be obtained, with a yield of 90.4%. The product can be directly used in subsequent reactions without further treatment..

[0060] Synthesis of 4bz-T:

[0061] Perform an anhydrous and anaerobic treatment on a 100 ml three-necked flask. Take 9 g of 4bz-SO2Cl (44.46 mmol) and place it in the flask and dissolve it in 20 ml of anhydrous acetonitrile, and place it in an ice-water bath. Take a 50 ml plastic centrifuge tube, add 6.84 g of trifluoromethanesulfonamide (TFSI, 45.96 mmol), 1.5 g of 4-dimethylpyridine (DMAP), and 18.5 ml of triethylamine (TEA) in sequence, and fill the centrifuge tube with anhydrous acetonitrile. After complete dissolution, slowly add it to the three-necked flask under the condition of an ice-water bath within 30 min. After adding, transfer it to an 85 °C oil bath and continue the reaction for 3 h. After the reaction is completed, remove acetonitrile by rotary evaporation, dissolve the mixture in 100 ml of dichloromethane, wash it twice with 50 ml of 4 wt% sodium bicarbonate solution, and then wash it twice with 50 ml of 1 M dilute hydrochloric acid. The organic phase is dried with anhydrous sodium sulfate, rotary evaporated to remove dichloromethane, and vacuum dried to obtain a brown-yellow solid product 4vbs-TFMSI-TEA (14.9 g, 35.8 mmol), with a yield of 80.3%. The product can be directly used in subsequent reactions without further treatment.

[0062] Synthesis of P-T-Li:

[0063] Dissolve the obtained brown liquid product above in ~150 ml of DMF, add 3.96 g of dihydroxy-terminated side-mercapto oligomer (PEBH-SH) and 550 mg of photoinitiator benzoin dimethyl ether (DMPA), stir well to dissolve, and then carry out an ultraviolet reaction for 3 h. After the reaction is completed, remove most of the DMF by rotary evaporation, add 75 ml of 4 wt% LiOH aqueous solution, and carry out rotary evaporation at 65 °C for 45 min to remove TEA while replacing the cation with Li. Subsequently, dilute the solution to 250 ml, dialyze it using a dialysis bag with Mn = 1000 for 2 d, and change the water every 8 h. After drying the water by rotary evaporation, 12.6 g of the final product P-T-Li is obtained, with a yield of 88.7%.

[0064] 2. Synthesis of ion-conducting polymer

[0065] Stir and react 0.3940 g of 4,4'-dicyclohexylmethane diisocyanate and 0.2500 g of polycarbonate diol (number-average molecular weight 1000) at 85 °C for 2.5 h under the catalysis of 0.0030 g of dibutyltin dilaurate and under argon protection, and add 1 mL of N,N-dimethylformamide for dilution during this period. Subsequently, add 0.1820 g of lithium salt of trifluoromethanesulfonimide polymer and react at 85 °C for 2 h, and add 2 mL of N,N-dimethylformamide for dilution during this period. Then add 0.1660 g of polyrotaxane (the host molecule is ethylene glycol with a number-average molecular weight of 4000, and the guest molecule is α-cyclodextrin with a hydroxypropylation rate of 64%) and react for 2 h, and add 18 mL of N,N-dimethylformamide for dilution during this period. After the reaction is completed, an ion-conducting polymer silicon anode binder solution with a molecular pulley effect is obtained.

[0066] Example 2

[0067] This example provides an ion-conducting polymer silicon anode binder solution with a molecular pulley effect.

[0068] The specific steps are as follows:

[0069] Stir and react 0.3940 g of 4,4'-dicyclohexylmethane diisocyanate and 0.3750 g of polytetrahydrofuran diol (number-average molecular weight 2000) at 75 °C for 3.5 h under the catalysis of 0.0045 g of stannous octoate and under argon protection, and add 4 mL of N-methylpyrrolidone for dilution during this period. Subsequently, add 0.3640 g of the lithium salt of trifluoromethanesulfonimide polymer prepared in Example 1 and react at 95 °C for 2 h, and add 2 mL of N-methylpyrrolidone for dilution during this period. Then add 0.1660 g of polyrotaxane (the host molecule is ethylene glycol with a number-average molecular weight of 4000, and the guest molecule is α-cyclodextrin with a hydroxypropylation rate of 64%) and react for 2 h, and add 18 mL of N-methylpyrrolidone for dilution during this period. After the reaction is completed, an ion-conducting polymer silicon anode binder solution with a molecular pulley effect is obtained.

[0070] Example 3

[0071] This example provides a silicon negative electrode slurry and a nano-silicon electrode sheet prepared based on an ion-conducting polymer silicon negative electrode binder with a molecular pulley effect.

[0072] The specific steps are as follows:

[0073] 1) Mix the binder solution obtained in Example 1 with nano-silicon with a diameter of 50 nm, carbon nanotubes, and lithiated polyacrylic acid, where the mass ratio of the binder:nano-silicon:carbon nanotubes:lithiated polyacrylic acid is 15%:70%:10%:5%. After stirring for 12 h, a silicon negative electrode slurry is obtained.

[0074] 2) Coat the obtained silicon negative electrode slurry on a copper foil with a thickness of 12 μm, and vacuum dry it at 85 °C for 12 h to obtain a nano-silicon electrode sheet.

[0075] Example 4

[0076] This example provides a silicon negative electrode slurry and a nano-silicon electrode sheet prepared based on an ion-conducting polymer silicon negative electrode binder with a molecular pulley effect.

[0077] The specific steps are as follows:

[0078] 1) Mix the binder solution obtained in Example 1 with nano-silicon with a diameter of 100 nm, Ketjen black, and polyacrylic acid, where the mass ratio of the binder:nano-silicon:Ketjen black:polyacrylic acid is 17.5%:65%:10%:2.5%. After stirring for 24 h, a silicon negative electrode slurry is obtained.

[0079] 2) Coat the obtained silicon negative electrode slurry on a copper foil with a thickness of 12 μm, and vacuum dry it at 65 °C for 20 h to obtain a nano-silicon electrode sheet.

[0080] Example 5

[0081] This example provides a silicon negative electrode slurry and a nano-silicon electrode sheet prepared based on an ion-conducting polymer silicon negative electrode binder with a molecular pulley effect

[0082] The specific steps are as follows:

[0083] 1) Mix the binder solution obtained in Example 2 with nano-silicon with a diameter of 30 nm, acetylene black, and polyvinylpyrrolidone, where the mass ratio of the binder:nano-silicon:acetylene black:polyvinylpyrrolidone is 17.5%:65%:10%:7.5%. After stirring for 12 h, a silicon negative electrode slurry is obtained.

[0084] 2) Coat the obtained silicon negative electrode slurry on a copper foil with a thickness of 12 μm, and vacuum dry it at 100 °C for 6 h to obtain a nano-silicon electrode sheet.

[0085] Example 6

[0086] This example provides a silicon anode slurry and a nano-silicon electrode sheet prepared based on an ion-conducting polymer silicon anode binder with a molecular pulley effect.

[0087] The specific steps are as follows:

[0088] 1) Mix the binder solution obtained in Example 2 with nano-silicon with a diameter of 50 nm, carbon nanotubes, and polyethylene glycol, where the mass ratio of the binder:nano-silicon:carbon nanotubes:ethylene glycol is 12.5%:75%:7.5%:5%. After stirring for 8 h, a silicon anode slurry is obtained.

[0089] 2) Coat the obtained silicon anode slurry on a copper foil with a thickness of 12 μm, and vacuum dry it at 85 °C for 12 h to obtain a nano-silicon electrode sheet.

[0090] Comparative Example 1

[0091] This example provides a silicon anode slurry and a nano-silicon electrode sheet prepared based on a PVDF binder.

[0092] The specific steps are as follows:

[0093] Dissolve PVDF (HSV900) in N,N-dimethylformamide to prepare a 10 wt% solution, and mix it with nano-silicon with a diameter of 50 nm and carbon nanotubes, where the mass ratio of the binder:nano-silicon:carbon nanotubes is 20%:70%:10%. After stirring for 12 h, a silicon anode slurry is obtained.

[0094] 2) Coat the obtained silicon anode slurry on a copper foil with a thickness of 12 μm, and vacuum dry it at 85 °C for 12 h to obtain a nano-silicon electrode sheet.

[0095] Example 7

[0096] Take the polymer binder materials prepared in Example 1 and Example 2 for a tensile test at a tensile rate of 1 mm / min. The results are shown in Table 1, proving that this type of binder has strong mechanical properties and is suitable for anode materials with large volume changes during charge and discharge such as crystalline silicon.

[0097] Table 1. Tensile test results of binder materials

[0098] Product Breaking Strain (%) Breaking Stress (MPa) Example 1 45 49.5 Example 2 275 20.4

[0099] Take the silicon electrode sheets prepared in Example 3, Example 4, Example 5, Example 6, and Comparative Example 1 for a peel force test at a peel rate of 100 mm / min. The results are shown in Table 2, proving that this type of binder has excellent adhesion and can generate a strong force with the current collector.

[0100] Table 2. Test Results of Peeling Force Performance of Silicon Electrode Sheets

[0101] Product Peeling Force (N) Example 3 4.1 Example 4 3.5 Example 5 2.7 Example 6 2.4 Comparative Example 1 0.5

[0102] The silicon electrode sheets prepared in Example 3, Example 4, Example 5, Example 6 and Comparative Example 1 were used for the first-cycle Coulombic efficiency test. The results are shown in Table 3, which proves that this type of binder can significantly improve the first-cycle Coulombic efficiency of silicon electrodes and increase the utilization rate of active materials.

[0103] Table 3. Test Results of First-Cycle Coulombic Efficiency of Silicon Electrode Sheets

[0104] Product Initial Coulomb Efficiency Example 3 90.7％ Example 4 88.5％ Example 5 88.0％ Example 6 88.7％ Comparative Example 1 75.8％

[0105] Figure 1 It is a graph of cyclic charge-discharge test data of a lithium-silicon half-cell assembled with the silicon electrode sheets corresponding to Example 3 and Comparative Example 1 at a current density of 0.1C. Example 3 shows more excellent cyclic stability than Comparative Example 1.

[0106] Figure 2 It is the AC impedance spectrum before cycling of a lithium-silicon half-cell assembled with the silicon electrode sheets corresponding to Example 3 and Comparative Example 1. The impedance of Example 3 is significantly lower than that of Comparative Example 1;

[0107] Figure 3 It is the AC impedance spectrum after cycling of a lithium-silicon half-cell assembled with the silicon electrode sheets corresponding to Example 3 and Comparative Example 1. The impedance of Example 3 is significantly lower than that of Comparative Example 1;

[0108] Figure 4 It is the scanning electron microscope image of the silicon electrode sheets corresponding to Example 3 and Comparative Example 1;

[0109] Figure 5 It is the infrared spectrum of the ion-conducting polymer silicon negative electrode binder material corresponding to Example 1. The urethane group, carbonate group, ether bond in the polymer main chain and the sulfonyl group in the side chain all produce obvious absorption peaks in the spectrum, and the polymer structure is clear and definite. The spectrum with corresponding characteristic functional groups can also be obtained by using the ion-conducting polymer silicon negative electrode binder material corresponding to Example 2.

[0110] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An ion-conductive polymer, characterized in that, It has the structure shown below: Wherein, A linking bond with R or hydrogen, provided that they are not all hydrogen; m1 = 90 - 100, m2 = 10 - 20, k = 2 - 20; R represents j = 1 - 17, provided that the total number of Rs connected to the same is 2 - 18; Among them, R1 is selected from: R2 is selected from polymer groups that are not reactive with isocyanates, the polymer groups containing one or more aliphatic, alicyclic and / or aromatic groups and having a number average molecular weight of 1000 - 4000; R3 is selected from: where n = 15 - 20.

2. The ion-conductive polymer according to claim 1, wherein The n is 18.

3. The ion-conductive polymer according to claim 1 or 2, characterized in that, R4 is not all hydrogen, and in each unit, Bonding key = 0.5:1 to 2:

1.

4. The ion-conductive polymer according to claim 1 or 2, wherein The R2 is selected from n1 = 10 - 40, n2 = 6 - 24.

5. A method for preparing an ion-conductive polymer as described in claim 1, characterized in that, The method comprises the following steps: Step 1: Catalytically react a polymer polyol, a diisocyanate, and a lithium salt of a bis-hydroxy-terminated sulfonimide polymer in a solvent to obtain a sulfonimide-type prepolymer; The polymer polyol is a polyol formed by a polymerization group that is non-reactive to isocyanate and a hydroxyl group, the polymerization group contains one or more aliphatic, alicyclic, and / or aromatic groups, and the polymer polyol has a number average molecular weight of 1000 - 4000; The diisocyanate is selected from one or more of 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; The lithium salt of the bis-hydroxy-terminated sulfonimide polymer has Structure; Step 2: Catalytically react the sulfonimide-type prepolymer prepared in Step 1 with a polyrotaxane in a solvent to obtain an ion-conductive polymer; The polyrotaxane has the following structure: or H, where: m1 = 90 - 100, m2 = 10 - 20.

6. The preparation method according to claim 5, characterized in that, The m2 = 14 - 18.

7. The preparation method according to claim 5, characterized in that, The polymer polyol is a polymer diol.

8. The preparation method according to claim 7, characterized in that, The polymer polyol is one or a mixture of poly(tetrahydrofuran), polycarbonate diol, etc.

9. The preparation method according to any one of claims 7-8, characterized in that, In each unit of the polyrotaxane, R4' H = 0.5:1 to 2:

1.

10. The preparation method according to any one of claims 7-8, characterized in that, The lithium salt of the bis-hydroxy-terminated sulfonimide polymer is prepared by reacting an MR3' salt with a compound of formula (a) and LiOH, Among them, the compound of formula (a) is where n = 15 - 20; M is an amine cation; R3’ is selected from 11. The preparation method according to claim 10, characterized in that, The n is 18.

12. The preparation method according to claim 10, characterized in that, The M is a tertiary amine cation.

13. A silicon anode binder, which comprises the ion-conductive polymer according to any one of claims 1 - 4.

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