A gel polymer electrolyte and a preparation method and application thereof

Abstract

The application relates to the technical field of solid electrolytes, in particular to a gel polymer electrolyte and a preparation method and application thereof, the preparation method of the gel polymer electrolyte comprises the following steps: S1, mixing polyethylene glycol diacrylate, N,N'-bis(acryloyl)cystamine and tris(2-hydroxyethyl)isocyanuric acid triacrylate in a protective atmosphere to obtain a polymer monomer mixture, then placing the polymer monomer mixture and an initiator in a lithium-based electrolyte, stirring, and obtaining a precursor solution; S2, solidifying the precursor solution to obtain the gel polymer electrolyte. The preparation method provided by the application is simple in process, raw materials are easy to obtain, and the method is easy to put into large-scale production. Meanwhile, the gel polymer electrolyte prepared has good mechanical properties and high room-temperature ionic conductivity.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to a gel polymer electrolyte, its preparation method, and its application. Background Technology

[0002] Over the past decade, flexible wearable electronics have experienced rapid development and have permeated into everyday life. Flexible wearable electronics are characterized by their light weight, small size, and ability to maintain functional stability under various mechanical deformations such as bending, twisting, and stretching, breaking through the application boundaries of traditional rigid electronic devices. However, these characteristics also place stringent requirements on the flexibility and adaptability of their integrated battery systems.

[0003] Traditional liquid electrolytes pose safety risks such as leakage, flammability, and volatility, making them unsuitable for the long-term reliable operation of flexible wearable electronic devices. While solid electrolytes offer significant advantages in safety, they are generally limited by technical bottlenecks such as low lithium-ion conductivity and excessive solid-solid interface contact resistance.

[0004] Gel polymer electrolytes, as a compromise system between liquid and solid states, can compensate for the shortcomings of both to some extent, but still face prominent problems such as slow lithium-ion migration rate, poor interface stability under dynamic deformation conditions, and insufficient mechanical strength. These factors together constitute the key obstacles currently restricting further improvement in the overall performance of flexible wearable electronic devices.

[0005] Therefore, preparing gel polymer electrolytes with high mechanical strength and high ionic conductivity is an urgent problem to be solved for the large-scale application of solid electrolytes. Summary of the Invention

[0006] The purpose of this invention is to provide a gel polymer electrolyte and its preparation method to solve the problems of slow lithium-ion migration rate, poor interface stability under dynamic deformation conditions, and insufficient mechanical strength of existing gel polymer electrolytes.

[0007] To achieve the above objectives, the present invention provides a method for preparing a gel polymer electrolyte, comprising the following steps: S1. Under a protective atmosphere, polyethylene glycol diacrylate, N,N'-bis(acryloyl)cystamine and tri(2-hydroxyethyl)isocyanurate triacrylate are mixed to obtain a polymerizable monomer mixture. Then, the polymerizable monomer mixture and initiator are placed in a lithium-based electrolyte and stirred to obtain a precursor solution. S2. The precursor solution is solidified to obtain a gel polymer electrolyte.

[0008] In this invention, the protective atmosphere preferably includes argon.

[0009] In this invention, the mass ratio of polyethylene glycol diacrylate (PEGDA), N,N'-bis(acryloyl)cysteine ​​(BAC), and tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) in S1 is preferably 0.2-1.5:0.1-0.7:0.2-1.2, more preferably 0.225-1.44:0.16-0.64:0.28-1.12, and even more preferably 0.225-0.36:0.16-0.219:0.28-0.356.

[0010] In this invention, the initiator in S1 preferably includes azobisisobutyronitrile (AIBN); the mass of the initiator preferably accounts for 1%-2% of the mass of the polymer monomer mixture, more preferably 1%.

[0011] In this invention, the CAS number of the polyethylene glycol diacrylate is 26570-48-9, the CAS number of the N,N'-bis(acryloyl)cystamine is 60984-57-8, and the CAS number of the tri(2-hydroxyethyl)isocyanurate triacrylate is 40220-08-4.

[0012] In this invention, the molecular weight of the polyethylene glycol diacrylate is 134.13.

[0013] In this invention, the lithium-based electrolyte in S1 is preferably a lithium bis(trifluoromethanesulfonyl)imide solution, and the concentration of the lithium bis(trifluoromethanesulfonyl)imide solution is preferably 1-1.5 mol / L, more preferably 1 mol / L.

[0014] In this invention, the solvent in the lithium bis(trifluoromethanesulfonylimide) solution is preferably composed of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC); the volume ratio of the dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is preferably 0.5-1:0.5-1:0.5-1, more preferably 1:1:1.

[0015] In this invention, the mass ratio of the polymer monomer mixture to the lithium-based electrolyte in S1 is preferably 1:4-6, more preferably 1:5.

[0016] In this invention, the stirring method described in S1 is preferably magnetic stirring, the stirring speed is preferably 450-600 rpm, more preferably 500 rpm, and the stirring time is preferably 20-24h, more preferably 24h.

[0017] In this invention, the curing temperature in S2 is preferably 55-65°C, more preferably 60°C, and the curing time is preferably 1.5-2.5h, more preferably 2h.

[0018] The present invention also provides a gel polymer electrolyte prepared by the above-described method for preparing gel polymer electrolytes.

[0019] The present invention also provides the application of the above-mentioned gel polymer electrolyte in the preparation of flexible electronic device batteries.

[0020] The present invention has the following beneficial effects: This invention provides a method for preparing a gel polymer electrolyte, comprising the following steps: S1, under a protective atmosphere, polyethylene glycol diacrylate, N,N'-bis(acryloyl)cysteine, and tri(2-hydroxyethyl)isocyanurate triacrylate are mixed to obtain a polymeric monomer mixture, and then the polymeric monomer mixture and an initiator are placed in a lithium-based electrolyte and stirred to obtain a precursor solution; S2, the precursor solution is solidified to obtain a gel polymer electrolyte.

[0021] This invention introduces tri(2-hydroxyethyl) isocyanurate triacrylate to make the structure of the gel polymer electrolyte more stable; polyethylene glycol diacrylate ensures that the gel polymer electrolyte has good flexibility, which allows the gel polymer electrolyte to better contact the interface, solving the problem of small contact area and high impedance of the "solid-solid interface" in traditional solid electrolytes; at the same time, N,N'-bis(acryloyl)cystamine is introduced, with its dynamic disulfide bond in its molecular structure as an energy dissipation center. When the gel polymer electrolyte is subjected to impact or stretching, the preferential breaking and recombination of disulfide bond can absorb a large amount of energy and prevent the rapid propagation of cracks, thereby significantly improving the toughness and tear resistance of the gel polymer electrolyte.

[0022] The method for preparing gel polymer electrolytes provided by this invention uses readily available raw materials, has a simple preparation process, and is suitable for large-scale production.

[0023] The polymer electrolyte prepared by the method for preparing gel polymer electrolyte provided by the present invention has excellent room temperature ionic conductivity, a wide electrochemical window, excellent half-cell cycle stability, high critical current density and excellent full-cell charge and discharge performance, while also having certain flexibility and mechanical properties.

[0024] Since the side reactions at the interface between conventional electrolytes and electrodes produce brittle and unstable solid electrolyte interface films, the polymer electrolyte provided by this invention can undergo adaptive recombination at the electrode interface to form a more flexible and stable interface layer, significantly improving stability.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1The infrared spectrum of the gel polymer electrolyte obtained in Example 1 of this invention; Figure 2 The graph shows the ionic conductivity of the button cell assembled in Application Example 1 of the present invention at different temperatures. Figure 3 This is a comparison diagram of the electrochemical window test of the coin cells assembled in Application Example 1 and Application Example 2 of this invention; Figure 4 A comparison chart of the critical current density tests of the coin cells assembled in Application Example 3 and Application Example 4 of this invention; Figure 5 The graph shows a comparison of the charge-discharge curves and discharge specific capacity of the button batteries assembled in Application Examples 5 and 6 of this invention at different rates at 30°C. in Figure 5 In the figure, 'a' represents the charge-discharge curves of the coin cells assembled in Application Examples 5 and 6 at different rates. Figure 5 In Figure b, there is a comparison of the discharge specific capacity of the coin cells assembled in Application Example 5 and Application Example 6. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0028] The lithium-based electrolyte used in the following examples is a 1 mol / L lithium bis(trifluoromethanesulfonyl)imide solution, purchased from KELOD.

[0029] Example 1 This embodiment provides a method for preparing a gel polymer electrolyte, comprising the following steps: S1. In a glove box filled with argon atmosphere, 0.225 g of polyethylene glycol diacrylate, 0.219 g of N,N'-bis(acryloyl)cystamine, and 0.356 g of tri(2-hydroxyethyl)isocyanurate triacrylate were mixed to obtain a monomer mixture. Then, the monomer mixture and 0.008 g of azobisisobutyronitrile were placed in 4 g of lithium-based electrolyte and magnetically stirred at 500 rpm for 24 h to obtain a precursor solution. S2. Place the precursor solution in an oven and keep it at 60°C for 2 hours to solidify it, thereby obtaining the gel polymer electrolyte (PTPB).

[0030] Example 2 This embodiment provides a method for preparing a gel polymer electrolyte, comprising the following steps: S1. In a glove box filled with argon atmosphere, 0.36 g of polyethylene glycol diacrylate, 0.16 g of N,N'-bis(acryloyl)cystamine, and 0.28 g of tris(2-hydroxyethyl)isocyanurate triacrylate were mixed to obtain a monomer mixture. Then, the monomer mixture and 0.008 g of azobisisobutyronitrile were placed in 4 g of lithium-based electrolyte and magnetically stirred at 500 rpm for 24 h to obtain a precursor solution. S2. Place the precursor solution in an oven and keep it at 60°C for 2 hours to solidify it, thereby obtaining a gel polymer electrolyte.

[0031] Example 3 This embodiment provides a method for preparing a gel polymer electrolyte, comprising the following steps: S1. In a glove box filled with argon atmosphere, 1.44 g of polyethylene glycol diacrylate, 0.64 g of N,N'-bis(acryloyl)cystamine, and 1.12 g of tri(2-hydroxyethyl)isocyanurate triacrylate were mixed to obtain a monomer mixture. Then, the monomer mixture and 0.032 g of azobisisobutyronitrile were placed in 16 g of lithium-based electrolyte and magnetically stirred at 500 rpm for 24 h to obtain a precursor solution. S2. Place the precursor solution in an oven and keep it at 60°C for 2 hours to solidify it, thereby obtaining a gel polymer electrolyte.

[0032] Comparative Example 1 This comparative example provides a method for preparing a gel polymer electrolyte, comprising the following steps: In a glove box filled with argon atmosphere, 0.39 g of polyethylene glycol diacrylate and 0.41 g of tris(2-hydroxyethyl)isocyanurate triacrylate were mixed to obtain a monomer mixture. Then, the monomer mixture and 0.008 g of azobisisobutyronitrile were placed in 4 g of lithium-based electrolyte and magnetically stirred at 500 rpm for 24 h to obtain a precursor solution. S2. Place the precursor solution in an oven and keep it at 60°C for 2 hours to solidify it, thereby obtaining a gel polymer electrolyte.

[0033] Application Example 1 The components were laid out in the following order: positive electrode shell - stainless steel disc - precursor solution (35 μL) prepared in Example 1 - PE separator - precursor solution (35 μL) prepared in Example 1 - stainless steel disc - negative electrode shell to obtain a semi-finished button cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0034] The positive electrode shell is made of pure titanium CR2032, the stainless steel disc is made of 304 stainless steel, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button cell shell.

[0035] Application Example 2 The components were laid out in the following order: positive electrode shell - stainless steel disc - precursor solution (35 μL) prepared in Comparative Example 1 - PE separator - precursor solution (35 μL) prepared in Comparative Example 1 - stainless steel disc - negative electrode shell to obtain a semi-finished button cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0036] The positive electrode shell is made of pure titanium CR2032, the stainless steel disc is made of 304 stainless steel, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button cell shell.

[0037] Application Example 3 The components were laid out in the following order: positive electrode shell - lithium sheet - precursor solution (35 μL) prepared in Example 1 - PE separator - precursor solution (35 μL) prepared in Example 1 - lithium sheet - negative electrode shell, to obtain a semi-finished coin cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0038] The positive electrode shell is a pure titanium battery shell CR2032, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button battery shell.

[0039] Application Example 4 The components were laid out in the following order: positive electrode shell - lithium sheet - precursor solution (35 μL) prepared in Comparative Example 1 - PE separator - precursor solution (35 μL) prepared in Comparative Example 1 - lithium sheet - negative electrode shell to obtain a semi-finished coin cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0040] The positive electrode shell is a pure titanium battery shell CR2032, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button battery shell.

[0041] Application Example 5 The components were laid out in the following order: positive electrode shell - lithium sheet - precursor solution (35 μL) prepared in Example 1 - PE separator - precursor solution (35 μL) prepared in Example 1 - lithium iron phosphate negative electrode sheet - negative electrode shell, to obtain a semi-finished button cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0042] The positive electrode shell is a pure titanium battery shell CR2032, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button battery shell.

[0043] Application Example 6 The components were laid out in the following order: positive electrode shell - lithium sheet - precursor solution (35 μL) prepared in Comparative Example 1 - PE separator - precursor solution (35 μL) prepared in Comparative Example 1 - lithium iron phosphate negative electrode sheet - negative electrode shell, to obtain a semi-finished button cell. The semi-finished button cell was placed in an oven and kept at 60°C for 2 hours to cure it, thus obtaining the button cell.

[0044] The positive electrode shell is a pure titanium battery shell CR2032, the PE separator is a 25μm thick microporous polyethylene separator, and the negative electrode shell is a 304 stainless steel button battery shell.

[0045] Characterization tests: The gel polymer electrolyte obtained in Example 1 was tested and analyzed using Fourier transform infrared spectroscopy, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the C=C vibration peaks in the gel polymer electrolyte (PTPB) have all disappeared, indicating that the gel polymer has been successfully synthesized.

[0046] Performance testing: The ionic conductivity of the coin cells obtained in Application Example 1 was tested at 20℃, 40℃, 60℃, 80℃, and 100℃, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the ionic conductivity of the coin cell assembled in Example 1 at 20℃ is calculated to be 0.93 × 10⁻⁶. -3 S / cm; the calculated ionic conductivity at 40℃ is 1.36 × 10⁻⁶. -3 S / cm; the calculated ionic conductivity at 60℃ is 1.78 × 10⁻⁶. -3 S / cm; the calculated ionic conductivity at 80℃ is 2.16 × 10⁻⁶. -3 S / cm; the calculated ionic conductivity at 100℃ is 2.44 × 10⁻⁶. -3 S / cm.

[0047] The electrochemical windows of the coin cells obtained in Application Examples 1 and 2 were tested under the following conditions: open-circuit voltage 6V, scan rate 1 mV / s. The results are as follows: Figure 3 As shown.

[0048] from Figure 3It can be seen that the width of the electrochemical window of the coin cell assembled in Application Example 1 is better than that in Application Example 2; the electrochemical window of the coin cell assembled in Application Example 1 is 4.6V.

[0049] The critical current density (CCD) of the coin cells assembled in Application Examples 3 and 4 was tested, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the CCD of the coin cell assembled in Example 3 is 1.15 mA cm⁻¹. -2 The CCD of the coin cell assembled in Application Example 4 is 0.6 mA cm⁻¹. -2 This indicates that the interface between the gel polymer electrolyte prepared in Example 1 and lithium metal (lithium sheet) is more stable.

[0050] The coin cells assembled in Application Examples 5 and 6 were tested for charge / discharge performance and discharge specific capacity at different rates at 30°C. The results are as follows: Figure 5 As shown. From Figure 5 As can be seen, the coin cell assembled in Application Example 5 exhibits superior rate performance and lower voltage polarization compared to Application Example 6.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a gel polymer electrolyte, characterized in that, Includes the following steps: S1. Under a protective atmosphere, polyethylene glycol diacrylate, N,N'-bis(acryloyl)cystamine and tri(2-hydroxyethyl)isocyanurate triacrylate are mixed to obtain a polymerizable monomer mixture. Then, the polymerizable monomer mixture and initiator are placed in a lithium-based electrolyte and stirred to obtain a precursor solution. S2. The precursor solution is solidified to obtain a gel polymer electrolyte.

2. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The mass ratio of polyethylene glycol diacrylate, N,N'-bis(acryloyl)cystamine, and tri(2-hydroxyethyl)isocyanurate triacrylate in S1 is 0.2-1.5:0.1-0.7:0.2-1.

2.

3. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The initiator mentioned in S1 includes azobisisobutyronitrile; The initiator accounts for 1%-2% of the mass of the polymer monomer mixture.

4. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The lithium-based electrolyte in S1 is a lithium bis(trifluoromethanesulfonyl)imide solution, and the concentration of the lithium bis(trifluoromethanesulfonyl)imide solution is 1-1.5 mol / L.

5. The method for preparing a gel polymer electrolyte according to claim 4, characterized in that, In the lithium bis(trifluoromethanesulfonylimide) solution, the solvent is composed of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate. The volume ratio of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is 0.5-1:0.5-1:0.5-1.

6. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The mass ratio of the polymer monomer mixture to the lithium-based electrolyte in S1 is 1:4-6.

7. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The stirring method described in S1 is magnetic stirring, the magnetic stirring speed is 450-600 rpm, and the magnetic stirring time is 20-24 hours.

8. The method for preparing a gel polymer electrolyte according to claim 1, characterized in that, The curing temperature in S2 is 55-65℃, and the curing time is 1.5-2.5h.

9. A gel polymer electrolyte prepared by the method for preparing a gel polymer electrolyte according to any one of claims 1-8.

10. The application of the gel polymer electrolyte of claim 9 in the preparation of flexible electronic device batteries.

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