Preparation method, product and application of polyoxime ester gel polymer electrolyte

Abstract

The present invention belongs to the field of polymer electrolytes, and more specifically, relates to a preparation method, product and application of a polyoxime ester gel polymer electrolyte. The present invention uses lithium salt to catalyze the reaction of ketoxime monomers and isocyanate monomers at room temperature, and adds diamine monomers and deep eutectic solvents to obtain a polyoxime ester gel polymer electrolyte in situ. When the polymer electrolyte is applied to lithium batteries, its oxime ester cross-linked network can give the electrolyte good mechanical properties, and the oxime ester bonds dynamically exchanged at room temperature can give the electrolyte excellent self-healing properties. At the same time, the hydrogen bond interaction between the polyoxime ester network and the deep eutectic solvent can promote the Li + The migration of deep eutectic solvent molecules can be inhibited, and the deep eutectic solvent molecules can be fixed in the polymer framework, thereby inhibiting their decomposition reaction on the electrode surface. The introduction of diamine can further improve the cycle stability of the electrolyte.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer electrolytes, and particularly relates to a preparation method of a polyoxime ester gel polymer electrolyte, the polyoxime ester gel polymer electrolyte and applications thereof. Background Art

[0002] Lithium metal batteries have a high theoretical specific capacity (3860mAh g -1 ) and the lowest redox potential (-3.04V), it is considered to be an alternative to lithium-ion batteries. However, due to the high reactivity of lithium metal, traditional liquid electrolytes easily react with it to form an unstable SEI layer, which creates defects on the anode surface and forms a locally concentrated lithium ion flux, which in turn causes lithium ions to deposit at the tip, forming lithium dendrites. Some lithium dendrites lose contact with lithium metal during the stripping process to form dead lithium, resulting in increased battery interface resistance, reduced coulombic efficiency, and even safety accidents. Therefore, it is very important to construct a safer solid polymer electrolyte.

[0003] Polyurethane-based polymer electrolytes have attracted widespread attention due to their excellent thermal stability and mechanical properties. At the same time, polyurethane is simple to synthesize and can be reverse-constructed into a network through polyols / amines and multi-arm isocyanates. The presence of soft and hard segments gives the polyurethane network excellent mechanical properties, thereby inhibiting the growth of lithium dendrites; the urethane bonds and urea groups in the polyurethane structure have a high dielectric constant, which can effectively complex lithium ions, promote the homogenization of lithium ion concentration, and achieve uniform deposition of lithium ions; in addition, polyurethane contains multiple hydrogen bond donors and acceptors, which can easily form hydrogen bond interactions with the electrode interface, and thus have good adhesion.

[0004] However, the preparation of polyurethane-based electrolytes requires the introduction of catalysts such as dibutyltin dilaurate. The presence of this non-electrolyte component will affect the cycle performance of the battery. At the same time, the polyurethane network is prone to cracks during long-term cycling, leading to a short circuit between the positive and negative electrodes, thereby causing serious safety problems. Summary of the Invention

[0005] In response to one or more of the above defects or improvement needs of the prior art, the present invention provides a preparation method, product and application of a polyoxime ester gel polymer electrolyte, which uses lithium salt to catalyze the room temperature addition polymerization reaction of ketoxime and isocyanate to obtain a polyoxime ester gel polymer electrolyte. The reaction conditions are mild and no other catalysts are required. The oxime ester cross-linked network can give the electrolyte good mechanical properties, and the oxime ester bonds dynamically exchanged at room temperature can give the electrolyte excellent self-healing properties. At the same time, the hydrogen bond interaction between the polyoxime ester network and the deep eutectic solvent can promote the Li +The migration of deep eutectic solvent molecules can be inhibited, and the deep eutectic solvent molecules can be fixed in the polymer framework, thereby inhibiting their decomposition reaction on the electrode surface; the introduction of diamine can further improve the cycle stability of the electrolyte.

[0006] To achieve the above object, according to a first aspect of the present invention, a method for preparing a polyoxime ester gel polymer electrolyte is provided, characterized in that it comprises the following steps:

[0007] S1: Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by a ketoxime monomer, a diamine monomer, an isocyanate monomer, a lithium salt, and a Lewis base is mixed and stirred to form a precursor solution;

[0008] S2: adding the precursor solution in step S1 dropwise onto the cellulose membrane, and performing addition polymerization reaction at room temperature under the catalysis of lithium salt to obtain a polymer electrolyte membrane.

[0009] As a further improvement of the present invention, the ketoxime monomer is one or more of glyoxime, methylglyoxime, dimethylglyoxime and 1,2-cyclohexanedione dioxime.

[0010] As a further improvement of the present invention, the diamine monomer is one or more of polyetheramine, polyoxyethylene diamine and O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol.

[0011] As a further improvement of the present invention, the relative molecular mass of the polyetheramine is 400-2000; the relative molecular mass of the polyoxyethylene diamine is 200-4000; and the relative molecular mass of the O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 500-2000.

[0012] As a further improvement of the present invention, the isocyanate monomer is HDI trimer and / or triphenylmethane triisocyanate.

[0013] As a further improvement of the present invention, in step S1, the molar ratio of the ketoxime monomer to the isocyanate monomer is 1 to 1.5:1, the added amount of the diamine monomer is less than or equal to 1 / 5 of the isocyanate monomer; the molar ratio of the lithium salt to the Lewis base is 1:4 to 1:12;

[0014] The lithium salt is one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonyl imide and lithium bisfluorosulfonyl imide; and the Lewis base is one or more of succinonitrile, cyclopentane and N-methylacetamide.

[0015] As a further improvement of the present invention, the mass fraction of the deep eutectic solvent in the precursor solution is 60-90%, so as to ensure that all monomers are completely dissolved and react to form a gel.

[0016] As a further improvement of the present invention, in step S2, the reaction time at room temperature is 5 to 120 minutes.

[0017] According to a second aspect of the present invention, a polyoxime ester gel polymer electrolyte is provided, which is prepared by the above-mentioned preparation method. The polyoxime ester gel polymer electrolyte is a thin film polymer electrolyte, and the thickness of the film is preferably 30 microns.

[0018] According to a third aspect of the present invention, there is provided a use of the polyoxime ester gel polymer electrolyte as a polymer electrolyte for a lithium ion battery.

[0019] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0020] (1) The present invention utilizes a lithium salt-catalyzed room-temperature addition polymerization reaction of ketoxime and isocyanate to produce a polyoxime ester gel polymer electrolyte. The reaction conditions are mild and no other catalysts are required. Compared with traditional polyurethane-based electrolytes, this method exhibits superior cycling performance. Furthermore, the preparation method is simple to operate and low-cost, making it promising for widespread application in the lithium battery field.

[0021] (2) The polyoxime ester gel polymer electrolyte prepared by the present invention contains a large number of oxime ester bonds that can be dynamically exchanged at room temperature, thereby endowing the electrolyte with excellent self-healing properties. When the polymer electrolyte is applied to lithium-ion batteries, it can automatically repair itself when cracks appear in the polymer during use, effectively resolving the safety issue caused by short circuits between the positive and negative electrodes at the cracks in the polymer electrolyte and extending the service life of the lithium battery.

[0022] (3) The polyoxime ester gel polymer electrolyte prepared by the present invention has a large number of hydrogen bonds, which makes it have good compatibility and adhesion with the electrode material. At the same time, the interaction between the oxime ester bond and the deep eutectic solvent not only promotes the + The migration of solvent molecules can be inhibited, and the solvent molecules can be fixed in the polyoxime ester framework, thereby inhibiting their decomposition reaction on the electrode surface.

[0023] (4) The ethoxy segment or propylene glycol segment of the diamine in the polyoxime ester gel polymer electrolyte prepared by the present invention can promote the migration of lithium ions. In addition, the crosslinking density of the polyurea network can be easily adjusted by changing the type and content of the diamine, thereby ensuring optimal performance.

[0024] (5) The isocyanate monomer in the polyoxime ester gel polymer electrolyte prepared by the present invention provides a cross-linking site, so that the electrolyte has excellent mechanical properties, can inhibit the growth of lithium dendrites, and further improve the cycle performance of the battery.

[0025] (6) The polyoxime ester gel polymer electrolyte prepared by the present invention can stably cycle 1000 times at a charge and discharge rate of 0.5C at room temperature, and its capacity retention rate is 77.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a photo of the self-healing performance of the polymer electrolyte in Example 1 of the present invention;

[0027] Figure 2 Graph showing changes in conductivity of the polymer electrolytes in Example 1 of the present invention and Comparative Example 1 as a function of temperature;

[0028] Figure 3 The charge-discharge performance and coulombic efficiency of the electrolyte in Example 1 of the present invention and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0030] The present invention provides a method for preparing a polyoxime ester gel polymer electrolyte, comprising the following steps:

[0031] S1: Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by a ketoxime monomer, a diamine monomer, an isocyanate monomer, a lithium salt, and a Lewis base is mixed and stirred to form a precursor solution;

[0032] S2: adding the precursor solution in step S1 dropwise onto the cellulose membrane, and performing addition polymerization reaction at room temperature under the catalysis of lithium salt to obtain a polymer electrolyte membrane.

[0033] In some embodiments, the ketoxime monomer is one or more of glyoxime, methylglyoxime, dimethylglyoxime, and 1,2-cyclohexanedione dioxime.

[0034] In some embodiments, the diamine monomer is one or more of polyetheramine, polyoxyethylenediamine, and O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol.

[0035] Among them, the relative molecular mass of polyetheramine is preferably 400-2000; the relative molecular mass of polyoxyethylene diamine is preferably 200-4000; and the relative molecular mass of O,O′-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is preferably 500-2000.

[0036] In some embodiments, the isocyanate monomer is HDI trimer and / or triphenylmethane triisocyanate.

[0037] In some embodiments, the lithium salt is one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl imide) and lithium bis(fluorosulfonyl imide); and the Lewis base is one or more of succinonitrile, cyclopentane and N-methylacetamide.

[0038] In some embodiments, in step S1, the molar ratio of the ketoxime monomer to the isocyanate monomer is 1 to 1.5:1, the amount of the diamine monomer added is less than or equal to 1 / 5 of the isocyanate monomer; the molar ratio of the lithium salt to the Lewis base is 1:4 to 1:12;

[0039] In some embodiments, the deep eutectic solvent comprises 60-90% by mass of the precursor solution to ensure that all monomers are completely dissolved and react to form a gel. Below 60% by mass, the monomers cannot dissolve, and above 90% by mass, the monomers cannot solidify to form a gel.

[0040] In some embodiments, the reaction time at room temperature in step S2 is 5 to 120 minutes.

[0041] The present invention also provides a corresponding polyoxime ester gel polymer electrolyte, which is prepared by the above preparation method. The polyoxime ester gel polymer electrolyte is a thin film polymer electrolyte, and the thickness of the film is preferably 30 microns.

[0042] The present invention also provides an application of a polyoxime ester gel polymer electrolyte, which is a polymer electrolyte for lithium-ion batteries. Since the polymer electrolyte of the present invention can be applied to lithium-ion batteries, the lithium salt used can be a lithium salt used in lithium batteries in the prior art (such as lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonyl imide, and lithium bisfluorosulfonyl imide).

[0043] It should also be noted that the thickness of the polyoxime ester gel polymer electrolyte membrane, produced by the lithium salt-catalyzed addition polymerization of ketoxime and isocyanate, can be flexibly adjusted according to actual needs. Commercial cellulose membranes can be used. The amount of precursor solution added is related to the thickness of the electrolyte membrane and can be adjusted according to the desired thickness.

[0044] The present invention uses lithium salt to catalyze the reaction of ketoxime monomers and isocyanate monomers at room temperature, and then adds diamine monomers and deep eutectic solvents to obtain a polyoxime ester gel polymer electrolyte in situ. When the polymer electrolyte is used in lithium batteries, its oxime ester cross-linked network can give the electrolyte good mechanical properties, and the oxime ester bonds dynamically exchanged at room temperature can give the electrolyte excellent self-healing properties. At the same time, the hydrogen bond interaction between the polyoxime ester network and the deep eutectic solvent can promote the Li + The migration of deep eutectic solvent molecules can be inhibited, and the deep eutectic solvent molecules can be fixed in the polymer framework, thereby inhibiting their decomposition reaction on the electrode surface. The introduction of diamine can further improve the cycle stability of the electrolyte.

[0045] In order to better understand the preparation method, product and application of the present invention, the following specific examples are provided:

[0046] Example 1

[0047] This embodiment provides a method for preparing a polyoxime ester gel polymer electrolyte membrane based on a lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate, which specifically includes the following steps:

[0048] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by dimethylglyoxime, a polyetheramine with a relative molecular mass of 2000, an HDI trimer, lithium bis(trifluoromethylsulfonyl)imide and N-methylacetamide is mixed and stirred uniformly to form a precursor solution; the molar ratio of dimethylglyoxime:polyetheramine:HDI trimer is 1.2:0.1:1, the molar ratio of lithium bis(trifluoromethylsulfonyl)imide and N-methylacetamide is 1:4, and the mass fraction of the polymer electrolyte is 90%.

[0049] Using a 0.5 mL dropper, 30 mg of the precursor solution was added dropwise to an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of a lithium salt for 5 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 5.0 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0050] Comparative Example 1

[0051] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by dimethylglyoxime, HDI trimer, lithium bis(trifluoromethylsulfonylimide) and N-methylacetamide is mixed and stirred evenly to form a precursor solution; wherein the molar ratio of dimethylglyoxime to HDI trimer is 1.5:1, the molar ratio of lithium bis(trifluoromethylsulfonylimide) to N-methylacetamide is 1:4, and the mass fraction of the polymer electrolyte is 90%.

[0052] Using a 0.5 mL dropper, 30 mg of the precursor solution was dripped onto an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of lithium salt. The reaction lasted for 10 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 3.25×10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0053] Figure 1 This photograph shows the self-healing properties of the electrolyte prepared in Example 1. The polyoxime ester gel electrolyte was cut in half with a scalpel and then spliced ​​at the cut. Finally, the electrolyte membrane was placed in a 60°C oven to observe the healing process and record the required healing time. This demonstrates that the introduction of oxime ester bonds imparts self-healing properties to the electrolyte material.

[0054] Figure 2 The conductivity of the electrolyte prepared in Example 1 and Comparative Example 1 changes with temperature. The electrochemical impedance spectrum of SPUPE was obtained by an electrochemical workstation (Autolab PGSTAT302 N), and the corresponding ionic conductivity was calculated according to the formula. Test method: In a glove box, SPUPE was sandwiched between two stainless steel sheets to assemble into a CR2032 button battery. The test was carried out at intervals of 10°C in the temperature range of 30 to 80°C and the impedance at each interval temperature was recorded. Then, according to the equation σ=L / (SR b ) to calculate the corresponding ionic conductivity, where L, S, R b Represent the thickness of the electrolyte membrane, the contact area between the electrolyte membrane and the stainless steel sheet, and the bulk resistance of the electrolyte membrane. It can be seen that after adding polyetheramine with a relative molecular weight of 2000, the conductivity of the electrolyte increases from 3.25×10 -4 S cm -1 Increased to 5.0×10 -4 S cm -1 .

[0055] Figure 3The charge and discharge performance and coulombic efficiency of the electrolyte prepared in Example 1 and Comparative Example 1. The long cycle stability and rate charge and discharge performance of SPUPE were characterized by the blue electricity test system (LANHE CT2001A). Test method: SPUPE was assembled into a Li||LFP battery. The cycle performance of the Li|SPUPE|LFP battery was tested at 25°C and in the voltage range of 2.5 to 4.2V. The constant current charge and discharge test was carried out for a long time at a charging rate of 0.5C. It can be seen that after adding polyetheramine with a relative molecular weight of 2000, the cycle life of the electrolyte was increased from 900 times to 1000 times, and the initial discharge specific capacity was increased to 143.4mAh g -1 , the capacity retention rate is 77.5%.

[0056] Comparative Example 2

[0057] Under anhydrous and oxygen-free conditions, dimethylglyoxime, polyetheramine with a relative molecular mass of 2000, HDI trimer and N-methylacetamide are mixed and stirred evenly to form a precursor solution; the molar ratio of dimethylglyoxime:polyetheramine:HDI trimer is 1.2:0.1:1, and the mass fraction of N-methylacetamide in the polymer electrolyte is 90%.

[0058] 30 mg of the above precursor solution was taken using a 0.5 mL dropper and added dropwise to the NKK 4030 cellulose membrane. Since no lithium salt was added, the polymerization reaction needed to be placed at 80° C. for 3 h to complete the reaction.

[0059] Example 2

[0060] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by glyoxime, polyetheramine with a relative molecular mass of 400, triphenylmethane triisocyanate, lithium hexafluorophosphate and sulfolane is mixed and stirred evenly to form a precursor solution; the molar ratio of glyoxime:polyetheramine:triphenylmethane triisocyanate is 1:0.2:1, the molar ratio of lithium hexafluorophosphate to sulfolane is 1:8, and the mass fraction of lithium hexafluorophosphate to sulfolane is 60%.

[0061] Using a 0.5 mL dropper, 30 mg of the precursor solution was added dropwise to an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of a lithium salt. The reaction lasted for 90 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 1.2 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0062] Example 3

[0063] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by methylglyoxime, polyoxyethylene diamine with a relative molecular mass of 200, HDI trimer, lithium difluorooxalatoborate and succinonitrile is mixed and stirred evenly to form a precursor solution; the molar ratio of methylglyoxime:polyoxyethylene diamine:HDI trimer is 1.2:0.1:1, the molar ratio of lithium difluorooxalatoborate and succinonitrile is 1:12, and the mass fraction of the polymer electrolyte is 70%.

[0064] Using a 0.5 mL dropper, 30 mg of the precursor solution was dripped onto an NKK 4030 cellulose membrane. A lithium salt-catalyzed addition polymerization reaction was carried out at room temperature to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 1.4 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0065] Example 4

[0066] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by 1,2-cyclohexanedione dioxime, polyoxyethylene diamine with a relative molecular mass of 4000, triphenylmethane triisocyanate, lithium tetrafluoroborate and N-methylacetamide is mixed and stirred evenly to form a precursor solution; the molar ratio of 1,2-cyclohexanedione dioxime:polyoxyethylene diamine:triphenylmethane triisocyanate is 1.5:0.1:1, the molar ratio of lithium tetrafluoroborate and N-methylacetamide is 1:4, and the mass fraction of the polymer electrolyte is 80%.

[0067] Using a 0.5 mL dropper, 30 mg of the precursor solution was dripped onto an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of a lithium salt. The reaction lasted for 120 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 2.1 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0068] Example 5

[0069] Under anhydrous and oxygen-free conditions, dimethylglyoxime, a deep eutectic solvent formed by O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (with a relative molecular mass of 500), HDI trimer, lithium trifluoromethanesulfonate, and sulfolane are mixed and stirred uniformly to form a precursor solution; the molar ratio of dimethylglyoxime:O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol:HDI trimer is 1.1:0.2:1, the molar ratio of lithium trifluoromethanesulfonate to sulfolane is 1:8, and the mass fraction of the polymer electrolyte is 90%.

[0070] Using a 0.5 mL dropper, 30 mg of the precursor solution was added dropwise to an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of a lithium salt. The reaction lasted for 30 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 2.4 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0071] Example 6

[0072] Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by 1,2-cyclohexanedione dioxime, O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol with a relative molecular mass of 2000, triphenylmethane triisocyanate, lithium bis(fluorosulfonyl)imide and succinonitrile is mixed and stirred uniformly to form a precursor solution; the molar ratio of 1,2-cyclohexanedione dioxime: O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol: triphenylmethane triisocyanate is 1.2:0.1:1, the molar ratio of lithium bis(fluorosulfonyl)imide to succinonitrile is 1:12, and the mass fraction of the polymer electrolyte is 80%.

[0073] Using a 0.5 mL dropper, 30 mg of the precursor solution was added dropwise to an NKK 4030 cellulose membrane. The addition polymerization reaction was carried out at room temperature under the catalysis of a lithium salt. The reaction lasted for 40 minutes to obtain a polyoxime ester gel polymer electrolyte membrane based on the lithium salt-catalyzed addition polymerization reaction of ketoxime and isocyanate. The ionic conductivity of the electrolyte membrane at room temperature was 1.8 × 10 -4 S cm -1 ; Lithium batteries are assembled in a glove box according to the lithium sheet, electrolyte membrane, and lithium iron phosphate positive electrode sheet.

[0074] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a polyoxime ester gel polymer electrolyte, characterized in that: The steps include: S1: Under anhydrous and oxygen-free conditions, a deep eutectic solvent formed by a lithium salt and a Lewis base, a dioxime monomer, a diamine monomer, and an isocyanate monomer are mixed and stirred to form a precursor solution; S2: adding the precursor solution in step S1 dropwise onto the cellulose membrane, and performing addition polymerization reaction at room temperature under the catalysis of lithium salt to obtain a polymer electrolyte membrane.

2. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: The dioxime monomer is one or more of glyoxime, methylglyoxime, dimethylglyoxime and 1,2-cyclohexanedione dioxime.

3. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: The diamine monomer is one or more of polyetheramine, polyoxyethylene diamine and O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol.

4. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 3, wherein: The relative molecular mass of the polyetheramine is 400-2000; the relative molecular mass of the polyoxyethylene diamine is 200-4000; and the relative molecular mass of the O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol is 500-2000.

5. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: The isocyanate monomer is HDI trimer and / or triphenylmethane triisocyanate.

6. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: In step S1, the molar ratio of the dioxime monomer to the isocyanate monomer is 1 to 1.5:1, the added amount of the diamine monomer is less than or equal to 1 / 5 of the molar amount of the isocyanate monomer; the molar ratio of the lithium salt to the Lewis base is 1:4 to 1:12; The lithium salt is one or more of lithium hexafluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonyl imide and lithium bisfluorosulfonyl imide; the Lewis base is one or more of succinonitrile, cyclopentane and N-methylacetamide.

7. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: The mass fraction of the deep eutectic solvent in the precursor solution is 60-90%, so as to ensure that all monomers are completely dissolved and react to form a gel.

8. The method for preparing a polyoxime ester gel polymer electrolyte according to claim 1, wherein: In step S2, the reaction time at room temperature is 5 to 120 minutes.

9. A polyoxime ester gel polymer electrolyte prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The polyoxime ester gel polymer electrolyte is a thin film-shaped polymer electrolyte.

10. Use of the polyoxime ester gel polymer electrolyte according to claim 9 as a polymer electrolyte for lithium ion batteries.

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