A polyimidazolyl electrolyte with self-repairing function and preparation method thereof

Abstract

The invention discloses a kind of polyimidazolyl electrolyte with self-repairing function and preparation method thereof, first prepare furan functionalized zirconium-based metal organic framework material (FU-UiO-66) and bistrifluoromethanesulfonyl imide as anionic maleimide functional type 1 vinyl imidazole ionic liquid during preparation, then add it in acetone to dissolve and disperse, then add bistrifluoromethanesulfonyl imide lithium, then add diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide as photoinitiator, be configured to casting solution, be coated on polytetrafluoroethylene plate film forming, and be placed under 365nm ultraviolet light source to solidify, dry, obtain the polyimidazolyl electrolyte with self-repairing function. The present invention obtains the polyimidazolyl electrolyte with self-repairing function, significantly extends the service life of electrolyte, effectively solves the problems such as crack, delamination or even fracture caused by repeated bending of flexible battery in prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrochemistry, and in particular to a polyimidazole-based electrolyte with a self-repairing function and a preparation method thereof. Background Art

[0002] With the rapid development of flexible wearable electronic devices, new flexibility requirements have been put forward for lithium-ion batteries (LIBs), which are energy supply devices. Traditional LIBs use flammable liquid electrolytes, which have leakage and serious thermal safety issues, making them unsuitable for application in flexible electronic facilities. To address the safety issues of traditional liquid electrolytes, the existing method is to "solidify" (fully solidify / gel) the liquid electrolyte, including fully solid-state inorganic electrolytes (ISEs), polymer solid electrolytes (SPEs), and polymer gel electrolytes (GPEs). On the other hand, LIBs integrated into flexible electronic devices face the risk of long-term bending deformation, which may induce fatigue cracks, delamination, and even fracture of the electrolyte in the device. Therefore, the design of flexible LIB electrolytes should have high flexibility and durability to meet the battery's dependence on bendability.

[0003] Self-healing materials, proposed in the 20th century, are a class of intelligent materials capable of repairing mechanical damage. They have great potential for extending the service life of materials and enhancing their fatigue resistance. Introducing reversible chemical bonds into a polymer matrix allows the material to heal multiple times under certain external stimuli (pH, light, heat, etc.). Based on the principle of reversible chemical bonds, a series of intrinsic self-healing materials, such as hydrogen bond / ionic bond double-crosslinked hydrogels and elastomers based on Diels-Alder (DA) reactions, have shown good results in improving material durability. Therefore, the development of electrolytes with self-healing functions is expected to solve the problem of durability. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a polyimidazole-based electrolyte with self-repairing function and a preparation method thereof, so as to obtain a polyimidazole-based electrolyte with self-repairing function, significantly extend the service life of the electrolyte, and effectively solve the problems of cracks, delamination and even breakage caused by repeated bending of flexible batteries in the prior art.

[0005] The present invention solves the above technical problems with the following technical solution: a method for preparing a polyimidazolyl-based electrolyte with self-repairing function is provided, comprising the following steps:

[0006] (1) Equimolar zirconium chloride and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide, glacial acetic acid is added dropwise, and then placed in a hydrothermal autoclave at 120°C for 12-24 hours, centrifuged, and washed to obtain amino-functionalized UiO-66; then amidated with furoic acid, added to dichloromethane containing 4-dimethylaminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and reacted at 30-60°C for 24-72 hours. Finally, filtered, washed, and dried to obtain FU-UiO-66;

[0007] (2) N-hydroxyethyl maleimide and 2-chloroethyl isocyanate were reacted at 40-80 ° C for 6-12 hours, washed, and dried to obtain chloride-functionalized maleimide (Cl-MA); Cl-MA and 1-vinylimidazole were refluxed in acetonitrile for 24-48 hours, precipitated with ether 2-4 times, and vacuum dried to obtain chloride-anion-functionalized maleimide-1-vinylimidazole ionic liquid (MA-VIM [Cl] ); dissolving lithium bis(trifluoromethanesulfonyl imide) and maleimide-functionalized 1-vinyl imidazolium ionic liquid in deionized water, stirring and reacting at room temperature for 12-24 hours until precipitation, and then separating, washing and drying in sequence to obtain maleimide-functionalized 1-vinyl imidazolium ionic liquid MA-VIM with bis(trifluoromethanesulfonyl imide) as the negative ion. [TFSI] ;

[0008] (3) The MA-VIM obtained in step (2) [TFSI] The FU-UiO-66 obtained in step (1) is added to acetone for dissolution and dispersion, and then lithium bis(trifluoromethanesulfonyl)imide is added, and then 1-2 wt% of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide by monomer mass is added to prepare a casting solution, which is coated on a polytetrafluoroethylene plate to form a film, and placed under a 365 nm ultraviolet light source for curing for 10-30 min, and dried to obtain a polyimidazolyl electrolyte with self-healing function.

[0009] Furthermore, in step (1), the molar ratio of 4-dimethylaminopyridine to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1:6-8.

[0010] Furthermore, 1-2 μL of glacial acetic acid was added to 10 mmol of zirconium chloride and 2-aminoterephthalic acid.

[0011] Furthermore, in step (2), the molar ratio of N-hydroxyethylmaleimide to 2-chloroethyl isocyanate is 1:1-3.

[0012] Furthermore, in step (2), the molar ratio of chlorine-functionalized maleimide (Cl-MA) to 1-vinylimidazole is 1-4:1.

[0013] Furthermore, in step (2), the molar ratio of bis(trifluoromethanesulfonyl)imide lithium maleimide functionalized 1-vinylimidazole ionic liquid is 1-2:1.

[0014] Furthermore, in step (3), MA-VIM [TFSI] and FU-UiO-66 mass ratio of 100:2-10.

[0015] Furthermore, in step (3), the amount of lithium bis(trifluoromethanesulfonylimide) added is 10-40 wt%.

[0016] Furthermore, in step (3), drying is performed at a temperature of 60-80°C.

[0017] The polyimidazolyl electrolyte with self-repairing function prepared by the preparation method of the polyimidazolyl electrolyte with self-repairing function.

[0018] The application of the above-mentioned polyimidazole-based electrolyte with self-repairing function in the preparation of flexible lithium-ion batteries.

[0019] A flexible lithium-ion battery comprises the above-mentioned polyimidazole-based electrolyte with self-repairing function.

[0020] The present invention has the following beneficial effects:

[0021] 1. The present invention produces a polyimidazole-based electrolyte with self-repairing function, which significantly extends the service life of the electrolyte and effectively solves the problems of cracks, delamination and even breakage caused by repeated bending of flexible batteries in the prior art.

[0022] 2. The present invention designs and prepares a polymerizable high-dissociation monomer, namely MA-VIm, as a matrix polymer; constructs a heat-resistant self-healing crosslinker containing a reversible DA reaction, namely FU-UiO-66, as a self-healing functional unit, adds lithium bis(trifluoromethanesulfonylimide) as a lithium source, and prepares a polyimidazolium ionic liquid-based self-healing electrolyte (SH-PIL) by coating and photocuring. The advantage of this invention is that the reversible DA reaction gives the electrolyte a self-healing function, which can repair fatigue damage that occurs in flexible electrolytes during long-term bending. The high affinity of the polyionic liquid for lithium enables the dissociation of lithium salts, resulting in high ionic conductivity.

[0023] 3. The reason for the repair in the present invention is that maleamide-functionalized vinylimidazole can undergo a dynamic and reversible Dierls-Alder reaction with furan-functionalized UiO-66, thereby repairing the broken chain segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The NMR spectrum of maleimide-functionalized 1-vinylimidazolium ionic liquid (MA-VIM) and the XRD spectrum of FU-UiO-66;

[0025] Figure 2 The SEM and TEM images of FU-UiO-66 are shown;

[0026] Figure 3 Schematic diagram of the cyclic repair performance of the self-healing electrolyte;

[0027] Figure 4 Schematic diagram of the self-repair performance of ionic conductivity. DETAILED DESCRIPTION

[0028] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0029] Example 1

[0030] A polyimidazolyl electrolyte with self-repairing function, the preparation method of which comprises the following steps:

[0031] (1) Equimolar zirconium chloride and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, glacial acetic acid was added dropwise, and then the mixture was placed in a hydrothermal autoclave at 120°C for 12 hours, centrifuged, and washed to obtain amino-functionalized UiO-66; the mixture was then amidated with furoic acid and added to dichloromethane containing 4-dimethylaminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and the mixture was reacted at 40°C for 24 hours. Finally, the mixture was filtered, washed, and dried to obtain FU-UiO-66; the molar ratio of 4-dimethylaminopyridine to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was 1:7;

[0032] (2) N-hydroxyethylmaleimide was reacted with 2-chloroethyl isocyanate at 60 ° C for 8 hours, washed, and dried to obtain chlorine-functionalized maleimide; Cl-MA and 1-vinylimidazole were refluxed in acetonitrile for 36 hours, precipitated with ether three times, and vacuum dried to obtain maleimide-functionalized 1-vinylimidazole ionic liquid; lithium bis(trifluoromethanesulfonyl)imide and maleimide-functionalized 1-vinylimidazole ionic liquid were dissolved in deionized water, stirred at room temperature for 12 hours until precipitation, and then separated, washed, and dried to obtain MA-VIM [TFSI] The molar ratio of N-hydroxyethylmaleimide to 2-chloroethyl isocyanate is 1:2, the molar ratio of Cl-MA to 1-vinylimidazole is 2:1, and the molar ratio of bis(trifluoromethanesulfonyl)imide lithium maleimide functionalized 1-vinylimidazole ionic liquid is 2:1;

[0033] (3) The MA-VIM obtained in step (2) [TFSI] The FU-UiO-66 obtained in step (1) was added to acetone in a mass ratio of 100:5 to dissolve and disperse, and then lithium bis(trifluoromethanesulfonyl)imide was added in an amount of 20wt%, and then 1wt% of the monomer mass of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide was added to prepare a casting solution, which was coated on a polytetrafluoroethylene plate to form a film, and placed under a 365nm ultraviolet light source for curing for 20min, and dried at 70°C to obtain a polyimidazolyl electrolyte with self-healing function.

[0034] Example 2

[0035] A polyimidazolyl electrolyte with self-repairing function, the preparation method of which comprises the following steps:

[0036] (1) Equimolar zirconium chloride and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, glacial acetic acid was added dropwise, and then the mixture was placed in a hydrothermal autoclave at 120°C for 12 hours, centrifuged, and washed to obtain amino-functionalized UiO-66; the mixture was then amidated with furoic acid and added to dichloromethane containing 4-dimethylaminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and the mixture was reacted at 30°C for 24 hours. Finally, the mixture was filtered, washed, and dried to obtain FU-UiO-66; the molar ratio of 4-dimethylaminopyridine to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was 1:6;

[0037] (2) N-hydroxyethylmaleimide was reacted with 2-chloroethyl isocyanate at 40-80 ° C for 6 hours, washed, and dried to obtain chlorine-functionalized maleimide; Cl-MA and 1-vinylimidazole were refluxed in acetonitrile for 24 hours, precipitated with ether three times, and vacuum dried to obtain maleimide-functionalized 1-vinylimidazole ionic liquid; lithium bis(trifluoromethanesulfonyl)imide and maleimide-functionalized 1-vinylimidazole ionic liquid were dissolved in deionized water, stirred at room temperature for 12 hours until precipitation, and then separated, washed, and dried to obtain MA-VIM [TFSI] The molar ratio of N-hydroxyethylmaleimide to 2-chloroethyl isocyanate is 1:1, the molar ratio of Cl-MA to 1-vinylimidazole is 1:1, and the molar ratio of bis(trifluoromethanesulfonyl)imide lithium maleimide functionalized 1-vinylimidazole ionic liquid is 1:1;

[0038] (3) The MA-VIM obtained in step (2) [TFSI]The FU-UiO-66 obtained in step (1) is added to acetone in a mass ratio of 100:2 to dissolve and disperse, and then lithium bis(trifluoromethanesulfonyl)imide is added in an amount of 10wt%, and then 1-2wt% of the monomer mass of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide is added to prepare a casting solution, which is coated on a polytetrafluoroethylene plate to form a film, and placed under a 365nm ultraviolet light source for curing for 10 minutes, and dried at 60°C to obtain a polyimidazolyl electrolyte with self-healing function.

[0039] Example 3

[0040] A polyimidazolyl electrolyte with self-repairing function, the preparation method of which comprises the following steps:

[0041] (1) Equimolar zirconium chloride and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, glacial acetic acid was added dropwise, and then the mixture was placed in a hydrothermal autoclave at 120°C for 24 hours, centrifuged, and washed to obtain amino-functionalized UiO-66; the mixture was then amidated with furoic acid and added to dichloromethane containing 4-dimethylaminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and the mixture was reacted at 60°C for 72 hours. Finally, the mixture was filtered, washed, and dried to obtain FU-UiO-66; the molar ratio of 4-dimethylaminopyridine to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was 1:8;

[0042] (2) N-hydroxyethylmaleimide was reacted with 2-chloroethyl isocyanate at 80 ° C for 12 hours, washed, and dried to obtain chlorine-functionalized maleimide; Cl-MA and 1-vinylimidazole were refluxed in acetonitrile for 48 hours, precipitated with ether three times, and vacuum dried to obtain maleimide-functionalized 1-vinylimidazole ionic liquid; lithium bis(trifluoromethanesulfonyl)imide and maleimide-functionalized 1-vinylimidazole ionic liquid were dissolved in deionized water, stirred at room temperature for 24 hours until precipitation, and then separated, washed, and dried to obtain MA-VIM [TFSI] The molar ratio of N-hydroxyethylmaleimide to 2-chloroethyl isocyanate is 1:3, the molar ratio of Cl-MA to 1-vinylimidazole is 4:1, and the molar ratio of bis(trifluoromethanesulfonyl)imide lithium maleimide functionalized 1-vinylimidazole ionic liquid is 2:1;

[0043] (3) The MA-VIM obtained in step (2) [TFSI]The FU-UiO-66 obtained in step (1) is dissolved and dispersed in acetone at a mass ratio of 100:10, and then lithium bis(trifluoromethanesulfonyl)imide is added in an amount of 40wt%, and then diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide is added in an amount of 1-2wt% by weight of the monomer mass to prepare a casting solution, which is coated on a polytetrafluoroethylene plate to form a film, and is placed under a 365nm ultraviolet light source for curing for 30min and dried at 80°C to obtain a polyimidazolyl electrolyte with self-healing function.

[0044] Experimental example

[0045] The NMR spectrum of the maleimide-functionalized 1-vinylimidazolium ionic liquid (MA-VIM) obtained in Example 1 and the XRD spectrum of FU-UiO-66 were obtained, as shown in FIG. Figure 1 shown; among them, Figure 1 a is the NMR spectrum, b is the XRD spectrum.

[0046] Depend on Figure 1 As can be seen from its NMR spectrum, peaks at 9.5, 8.1, and 7.9 ppm correspond to the characteristic H on the imidazole ring, 7.5 and 5.3 ppm correspond to the characteristic H on the vinyl group on the imidazole ring, 4.3 ppm corresponds to the H on the methylene group adjacent to the urea group, and near 3.5 is the characteristic peak of the H on the methylene group. The characteristic peaks near 7-8, 26, and 44° in the XRD spectrum well demonstrate the successful synthesis of FU-UiO-66.

[0047] The SEM and TEM morphologies of FU-UiO-66 were obtained respectively, as shown in Figure 2 shown; among them, Figure 1 a is the SEM morphology image, and b is the TEM morphology image.

[0048] Depend on Figure 1 It can be seen that FU-UiO-66 presents an octahedral structure and the particle size distribution is relatively uniform; it also shows that the particle size of octahedral FU-UiO-66 is about 120nm.

[0049] Take a section of intact electrolyte and stretch it to test its mechanical properties. Then cut the electrolyte and perform contact self-repair. Then test the mechanical properties again to see the difference with the original mechanical properties. Multiple repairs are repeated break-repair procedures. The cyclic repair performance of the self-repairing electrolyte is as follows: Figure 3 At the same time, the ionic conductivity of the battery was measured by AC impedance method using a symmetrical stainless steel cell. The test results are shown in Figure 4 shown.

[0050] Depend on Figure 3 It can be seen that after the electrolyte breaks, it recovers to more than 80% to 90% of its original mechanical properties through self-repair.

[0051] Depend on Figure 4 It can be seen that the intact electrolyte has a high conductivity of up to 2.35mS cm -1 The ionic conductivity of the electrolyte can be restored to more than 90% after fracture-self-repair, indicating that the electrolyte also has ion self-repairing properties.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. 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 polyimidazolyl electrolyte with self-repairing function, characterized in that: The following steps are involved: (1) Equimolar zirconium chloride and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide, glacial acetic acid is added dropwise, and then placed in a hydrothermal autoclave at 120°C for 12-24 hours, centrifuged, and washed to obtain amino-functionalized UiO-66; then amidated with furoic acid, added to dichloromethane containing 4-dimethylaminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and reacted at 30-60°C for 24-72 hours. Finally, filtered, washed, and dried to obtain FU-UiO-66; (2) reacting N-hydroxyethyl maleimide with 2-chloroethyl isocyanate at 40-80°C for 6-12h, washing, and drying to obtain chloride-functionalized maleimide; refluxing chloride-functionalized maleimide with 1-vinylimidazole in acetonitrile for 24-48h, precipitating with ether 2-4 times, and vacuum drying to obtain a maleimide-functionalized 1-vinylimidazole ionic liquid with chloride anion; dissolving lithium bis(trifluoromethanesulfonyl imide) and maleimide-functionalized 1-vinylimidazole ionic liquid in deionized water, stirring at room temperature for 12-24h until precipitation, and then separating, washing, and drying to obtain a maleimide-functionalized 1-vinylimidazole ionic liquid with bis(trifluoromethanesulfonyl imide) as anion; (3) The maleimide-functionalized 1-vinylimidazolium ionic liquid containing bistrifluoromethanesulfonyl imide as the negative ion obtained in step (2) and the FU-UiO-66 obtained in step (1) are dissolved and dispersed in acetone, and then lithium bistrifluoromethanesulfonyl imide is added, followed by 1-2 wt% of the monomer mass of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide to prepare a casting solution, which is coated on a polytetrafluoroethylene plate to form a film, and placed under a 365 nm ultraviolet light source for curing for 10-30 min, and dried to obtain a polyimidazole-based electrolyte with self-healing function.

2. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (1), the molar ratio of 4-dimethylaminopyridine to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1:6-8.

3. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (2), the molar ratio of N-hydroxyethylmaleimide to 2-chloroethyl isocyanate is 1:1-3.

4. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (2), the molar ratio of chloro-functionalized maleimide to 1-vinylimidazole is 1-4:

1.

5. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (2), the molar ratio of bis(trifluoromethanesulfonyl)imide lithium maleimide functionalized 1-vinylimidazole ionic liquid is 1-2:

1.

6. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (3), the mass ratio of the maleimide-functionalized 1-vinylimidazolium ionic liquid with bis(trifluoromethanesulfonyl)imide as the negative ion to FU-UiO-66 is 100:2-10.

7. The method for preparing a polyimidazolyl electrolyte having a self-repairing function according to claim 1, wherein: In step (3), the amount of lithium bis(trifluoromethanesulfonyl imide) added is 10-40 wt%.

8. A polyimidazolyl electrolyte with self-repairing function obtained by the method for preparing a polyimidazolyl electrolyte with self-repairing function according to any one of claims 1 to 7.

9. Use of the polyimidazole-based electrolyte with self-repairing function according to claim 8 in the preparation of flexible lithium-ion batteries.

10. A flexible lithium-ion battery, characterized in that: The invention comprises the polyimidazole-based electrolyte with self-repairing function as claimed in claim 8.

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