阅读说明：本技术 一种自修复共混聚合物电解质及其制备方法 (Self-repairing blended polymer electrolyte and preparation method thereof ) 是由 丁赵波 罗承东 赵玉辉 罗英 杜英杰 刘雯 郭瑞 裴海娟 解晶莹 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种自修复共混聚合物电解质及其制备方法,包含：步骤1,NH-(2)-PEG-NH-(2)和硫脲以及苯二亚甲基二异氰酸酯溶解,在20～80℃的温度和氮气气氛下发生聚合反应合成具有自修复硫脲基团和脲基基团的聚合物溶液Ⅰ；步骤2,将聚合物溶液Ⅰ倒入培养皿中,在真空干燥箱中加热24h～72h挥发溶剂得到固态聚合物Ⅱ；步骤3,固态聚合物Ⅱ溶解到碳酸亚乙烯酯溶剂中,依次加入引发剂和锂盐,室温在氮气气氛下搅拌8～24h形成均匀的聚合物电解质溶液Ⅲ；步骤4,45～80℃在引发剂作用下原位聚合形成固态自修复共混聚合物电解质。本发明合成的共混自修复聚合物电解质膜可塑性高、柔性强、与电极之间的界面阻抗低、离子电导率高和操作简单等特点。(The invention discloses a self-repairing polymer blend electrolyte and a preparation method thereof, wherein the self-repairing polymer blend electrolyte comprises the following components: step 1, NH 2 ‑PEG‑NH 2 Dissolving the polymer solution I with thiourea and xylylene diisocyanate, and performing polymerization reaction at the temperature of 20-80 ℃ in a nitrogen atmosphere to synthesize a polymer solution I with self-repairing thiourea groups and carbamido groups; step 2, pouring the polymer solution I into a culture dish, heating the culture dish in a vacuum drying oven for 24 to 72 hours to volatilize the solvent to obtain a solid polymerII, II; step 3, dissolving the solid polymer II into a vinylene carbonate solvent, sequentially adding an initiator and a lithium salt, and stirring for 8-24 hours at room temperature in a nitrogen atmosphere to form a uniform polymer electrolyte solution III; and 4, carrying out in-situ polymerization at 45-80 ℃ under the action of an initiator to form the solid self-repairing blended polymer electrolyte. The blended self-repairing polymer electrolyte membrane synthesized by the method has the characteristics of high plasticity, strong flexibility, low interface impedance with electrodes, high ionic conductivity, simplicity in operation and the like.)

1. A method for preparing a self-repairing polymer blend electrolyte, which is characterized by comprising the following steps:

step 1, NH₂-PEG-NH₂Dissolving thiourea and xylylene diisocyanate in a mixed solvent of dimethyl sulfoxide and chloroform, and performing polymerization reaction at the temperature of 20-80 ℃ in a nitrogen atmosphere to synthesize a polymer solution I with self-repairing thiourea groups and carbamido groups;

step 2, pouring the polymer solution I into a culture dish, and heating the culture dish in a vacuum drying oven for 24-72 hours to volatilize the solvent to obtain a solid polymer II;

step 3, dissolving the solid polymer II into a vinylene carbonate solvent, sequentially adding an initiator and a lithium salt, and stirring for 8-24 hours at room temperature in a nitrogen atmosphere to form a uniform polymer electrolyte solution III;

and 4, injecting the polymer electrolyte solution III into the battery, and carrying out in-situ polymerization at 45-80 ℃ under the action of an initiator to form a solid self-repairing polymer blend electrolyte or transferring the polymer electrolyte III into a mold to initiate polymerization under a heating condition to form the solid self-repairing polymer blend electrolyte membrane.

2. The method for preparing the self-repairing polymer blend electrolyte according to claim 1, wherein the mixed solvent in the step 1 further comprises any one or a combination of any two or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and acetone.

3. The method for preparing a self-healing polymer blend electrolyte according to claim 1, wherein in step 1, NH is added to the electrolyte₂-PEG-NH₂: thiourea: the molar ratio of the xylylene diisocyanate is 2: 1: 1.

4. the method for preparing self-repairing polymer blend electrolyte according to claim 1, wherein in step 3, the initiator is any one or a combination of any two or more of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate and dimethyl azodiisobutyrate.

5. The method for preparing the self-repairing polymer blend electrolyte according to claim 1, wherein in the step 3, the lithium salt comprises any one or a combination of any two or more of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium dioxalate borate, lithium hexafluoroarsenate and lithium bis (oxalato) borate LiBOB of organic lithium salt, lithium difluoro (oxalato) borate LiDFOB, lithium bis (difluorosulfonimide) LiFSI and lithium bis (trifluoromethylsulfonyl) imide LiTFSI.

6. The preparation method of the self-repairing polymer blend electrolyte as claimed in claim 1, wherein in the step 3, the mass ratio of the vinylene carbonate to the solid polymer II is 5: 1-15: 1.

7. the preparation method of the self-repairing polymer blend electrolyte as claimed in claim 1, wherein the lithium salt accounts for 5-50%, preferably 10-30% of the total mass of the solid self-repairing polymer blend electrolyte membrane.

8. The preparation method of the self-repairing polymer electrolyte blend as claimed in claim 1, wherein the thickness of the polymer electrolyte formed by in-situ polymerization in the step 4 is 10-100 μm, preferably 20-50 μm, and the thickness of the self-repairing polymer electrolyte blend membrane formed by ex-situ polymerization is 100-800 μm, preferably 100-300 μm.

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

10. A lithium-based battery comprising the self-healing blended polymer electrolyte of claim 9.

Technical Field

The invention relates to the field of energy storage, in particular to a preparation method of a self-repairing polymer electrolyte and application of the self-repairing polymer electrolyte in a lithium-based battery.

Background

Compared with the traditional battery, the lithium ion battery has the advantages of high energy density, high average output voltage, small self-discharge, high charging efficiency, quick charge and discharge, wide working temperature range, environmental friendliness, long service life and the like, and is widely applied to electronic equipment such as electric automobiles, mobile phones, computers and the like as energy storage equipment. However, the conventional lithium ion battery uses liquid electrolyte as a medium for lithium ion transmission in the battery, and the liquid electrolyte is easy to cause risk accidents such as spontaneous combustion, volatilization and explosion of the battery due to low boiling point, low flash point and other factors, so the conventional lithium ion battery faces huge safety risks. The polymer electrolyte membrane has higher safety by replacing organic electrolyte, has the advantages of high flexibility, strong plasticity and the like, and can be more widely applied to some wearable electronic equipment in the future.

CN108110315B discloses a method for synthesizing a self-repairing gel polymer electrolyte, which comprises adding polydimethylsiloxane and polyvinylidene fluoride into a solvent for ultrasonic dissolution, adding a cross-linking agent to improve the mechanical properties of the polymer, volatilizing the solvent to obtain a polymer film, and then soaking the polymer film in an electrolyte to obtain the final gel polymer electrolyte, but the polymer electrolyte film synthesized by the method has a large interfacial resistance when assembling a battery, and if the thickness of the synthesized film is too thin, the mechanical properties of the synthesized film are insufficient, and the synthesized film is easy to break and generate large cracks when being peeled off from a glass plate.

CN109728342A discloses a method for synthesizing a composite self-repairing solid electrolyte, which synthesizes Ga doped with a polymer of ureido groups with self-repairing property_0.25Li_6.25La₃Zr₂O₁₂The inorganic solid electrolyte is used for preparing a composite self-repairing solid electrolyte which can inhibit the growth of lithium dendrites and prolong the cycle life of the battery. However, in the process of coating the inorganic solid electrolyte and the polymer doping on the polytetrafluoroethylene substrate by the volatile solvent, the inorganic ceramic electrolyte is deposited on the bottom of the polymer material due to high density of the inorganic ceramic electrolyte, so that the inorganic ceramic is unevenly dispersed in the polymer, and according to the recent literature, the active inorganic ceramic electrolyte and the inert inorganic ceramic material doping are not obviously different, the ion conduction of the active inorganic ceramic electrolyte is mainly transferred between the polymer and the inorganic ceramic material interface, and the Ga doping is performed_0.25Li_6.25La₃Zr₂O₁₂The cost of the electrolyte will be further increased.

Disclosure of Invention

The invention aims to alleviate the problems of the electrolyte and meet the application of an energy storage device in complex environments such as folding, bending, beating, stretching, shearing and dropping, and designs a blended polymer electrolyte with a self-repairing function synthesized by in-situ polymerization to replace the traditional form of combining an organic electrolyte and a diaphragm, so that the safety performance of a battery is improved, and the introduction of the intelligent self-repairing function can enable the polymer electrolyte to have better stretching, bending and folding resistant effects, can be applied in the complex environments, inhibit the growth of lithium dendrites, repair electrolyte cracks and holes caused by the growth and compression of the lithium dendrites, and prolong the service life of the battery.

In order to achieve the above object, the present invention provides a method for preparing a self-healing polymer blend electrolyte, comprising:

step 1, NH₂-PEG-NH₂Dissolving thiourea and xylylene diisocyanate in a mixed solvent of dimethyl sulfoxide and chloroform, and performing polymerization reaction at the temperature of 20-80 ℃ in a nitrogen atmosphere to synthesize a polymer solution I with self-repairing thiourea groups and carbamido groups;

step 2, pouring the polymer solution I into a culture dish, and heating the culture dish in a vacuum drying oven for 24-72 hours to volatilize the solvent to obtain a solid polymer II;

step 3, dissolving the solid polymer II into a vinylene carbonate solvent, sequentially adding an initiator and a lithium salt, and stirring for 8-24 hours at room temperature in a nitrogen atmosphere to form a uniform polymer electrolyte solution III;

and 4, injecting the polymer electrolyte solution III into the battery, and carrying out in-situ polymerization at 45-80 ℃ under the action of an initiator to form a solid self-repairing polymer blend electrolyte or transferring the polymer electrolyte III into a mold to initiate polymerization under a heating condition to form the solid self-repairing polymer blend electrolyte membrane.

Optionally, the mixed solvent in step 1 further comprises any one or a combination of any two or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and acetone.

Optionally, in step 1, NH₂-PEG-NH₂: thiourea: the molar ratio of the xylylene diisocyanate is 2: 1: 1.

optionally, in step 3, the initiator is any one or a combination of any two or more of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate peroxylauroyl, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and dimethyl azobisisobutyrate.

Optionally, in step 3, the lithium salt includes any one or a combination of any two or more of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium dioxalate borate, lithium hexafluoroarsenate, and lithium bis (oxalato) borate LiBOB of an organic lithium salt, lithium difluorooxalato borate lidob, lithium bis (difluorosulfonimide) LiFSI, and lithium bis (trifluoromethylsulfonyl) imide LiTFSI.

Optionally, in the step 3, the mass ratio of the vinylene carbonate to the solid polymer II is 5: 1-15: 1.

optionally, the lithium salt accounts for 5-50%, preferably 10-30% of the total mass of the solid self-repairing polymer blend electrolyte membrane.

Optionally, the thickness of the polymer electrolyte formed by in-situ polymerization in the step 4 is 10-100 μm, preferably 20-50 μm, and the thickness of the self-repairing blended polymer electrolyte membrane formed by ex-situ polymerization reaches 100-800 μm, preferably 100-300 μm.

The invention also provides the self-repairing polymer blend electrolyte prepared by the preparation method of the self-repairing polymer blend electrolyte.

The invention also provides a lithium-based battery which comprises the self-repairing blended polymer electrolyte.

According to the invention, the interface impedance is reduced by adopting an in-situ polymerization mode, meanwhile, the electrolyte with thinner thickness can be designed through in-situ polymerization, and the characteristics of two materials can be exerted by blending two polymers, so that the polymer electrolyte has the characteristics of higher mechanical strength, toughness, flexibility and the like, cracks and holes generated in the use process of the electrolyte can be repaired, and the problems of battery service life reduction or short circuit and the like caused by electrolyte fracture are prevented.

The blended polymer electrolyte provided by the invention has the characteristics of self-repairing property, high flexibility, strong plasticity, good stability and the like. The aim of automatic healing of the material is achieved by heating chemical bond recombination which can stimulate the breakage of the polymer electrolyte at a certain temperature. The polymer electrolyte can be synthesized in an in-situ polymerization mode, so that the interface impedance between the electrolyte and an electrode is reduced, the preparation process is simple, the operation is easy, the method is suitable for large-scale production, and the method is expected to be applied to the aspects of electronic skin, flexible devices, intelligent wearing (such as intelligent watches, intelligent bracelets, intelligent glasses and intelligent clothes), solid electrolyte and the like.

Drawings

FIG. 1 is a graph of the self-healing effect of the blended self-healing polymer electrolyte prepared in example 1.

Fig. 2 is a Li-Li symmetric battery polarization voltage plot for the blended self-healing polymer electrolyte prepared in example 1.

Fig. 3 is an alternating current impedance spectrum of a stainless steel symmetrical battery composed of the blended self-repairing polymer electrolyte tested under different temperature conditions by the blended self-repairing polymer electrolyte prepared in example 1.

FIG. 4 is an infrared spectrum of a blended self-healing polymer electrolyte prepared in example 1.

Fig. 5 is a glass transition temperature spectrum of the blended self-healing polymer electrolyte prepared in example 1.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The experimental procedures in all the following examples are conventional and the materials and drugs used are normally commercially available.

EXAMPLE 1 preparation of self-healing Polymer blend electrolyte

(1) Reacting NH₂-PEG-NH₂Adding thiourea and xylylene diisocyanate into a mixed solvent of chloroform and dimethyl sulfoxide, heating and stirring at 60 ℃ in a nitrogen atmosphere for dissolving for 24 hours, and performing addition reaction to synthesize a polyurethane polymer solution;

(2) transferring the polymer solution obtained in the step (1) into a mould, and heating the mould in a vacuum drying oven at 80 ℃ for 24 hours to remove the solvent to obtain a solid polymer;

(3) dissolving the solid polymer in the step (2) in a vinylene carbonate solvent, heating at 60 ℃ in a nitrogen atmosphere to completely dissolve the solid polymer, then cooling to room temperature, adding initiators of azobisisobutyronitrile and lithium salt LiDFOB, and stirring at room temperature for 12 hours to form a uniform polymer electrolyte solution;

(4) and (4) injecting the polymer electrolyte solution obtained in the step (3) between the anode and the cathode of the battery to assemble the battery, and heating at 60 ℃ for 12h to initiate vinylene carbonate to polymerize in situ to form the blended self-repairing polymer electrolyte. According to a repair test, as shown in fig. 1, the polymer film can have 80% of repair effect on the scars visible to the naked eyes within 5min under the condition of room temperature.

(5) Or transferring the polymer solution obtained in the step (3) into a culture dish, heating for 12 hours at 60 ℃ in a nitrogen atmosphere to initiate polymerization to obtain a compact and uniform blended self-repairing polymer electrolyte membrane, punching the polymer electrolyte membrane into a 18mm round piece by using an 18mm punch, and placing the round piece between a positive electrode and a negative electrode to assemble the battery.

The NH₂-PEG-NH₂: thiourea: the molar ratio of the xylylene diisocyanate is 2: 1: vinylene carbonate and (NH)₂-PEG-NH₂+ thiourea + xylylene diisocyanate) in a total mass ratio of 10: 1, the lithium salt accounts for 25 percent of the total mass of the material.

Injecting the polymer electrolyte solution between two stainless steel electrodes to assemble a symmetrical battery through in-situ polymerization, or installing a self-repairing blended polymer electrolyte membrane between the stainless steel electrodes to assemble the battery, measuring the alternating current impedance spectrum of the battery and testing other electrochemical performances by using an electrochemical workstation.

Assembling polymer electrolyte and lithium intoThe alternating current impedance of the symmetrical battery is measured, the measuring instrument is an alternating current impedance instrument, and the test frequency from low frequency to high frequency is as follows: 0.1 to 100 KHz. The test results are shown in FIG. 2, where the Li-Li symmetrical cell is at 0.25mA/cm²The polarized voltage is kept within 0.1V within 17500min of circulation under the current density.

The linear scanning interval is 0-6V; the sweeping speed is 1 mV/s; the particle size and dimension of the polymer electrolyte samples were measured by transmission electron microscopy.

The microscopic morphology of the polymer electrolyte surface was analyzed by scanning electron microscopy (SEM S4800) to observe the pore size and morphology of the surface.

Qualitative analysis of the samples by X-ray diffraction (XRD)

The positive and negative electrode materials and the self-repairing blended polymer electrolyte are assembled into a battery, the multiplying power performance and the cycle life of the battery are tested by using electrochemical testing equipment such as blue electricity and the like, and the battery is subjected to cyclic voltammetry by using an electrochemical workstation. As shown in FIG. 3, the AC impedance spectra of the symmetrical stainless steel cells composed of the blended self-healing polymer electrolyte were measured at different temperatures and measured at room temperature to be 12.32. omega. cm²Ion conductivity of 1.58X 10^-3S cm^-1。

The infrared spectrogram of the blended self-repairing polymer electrolyte prepared in the embodiment 1 is shown in fig. 4 and ranges from 3400 cm to 3500cm^-1The broad peak in the vicinity represents the stretching vibration peak of the hydroxyl group at 1100cm^-1Is the C-O-C stretching vibration peak.

Fig. 5 is a glass transition temperature spectrum of the blended self-healing polymer electrolyte prepared in example 1, and it can be seen from the graph that the glass transition temperature of the polymer electrolyte is around 25 ℃, and the flexibility is good at room temperature. Example 2 preparation of gel electrolyte

The difference from example 1 is (NH)₂-PEG-NH₂+ thiourea + xylylene diisocyanate): the mass ratio of vinylene carbonate is 1: the self-repairing polymer blend electrolyte prepared by the method of example 1 is tested under the same conditions as in example 1.

Example 3 preparation of gel electrolyte

The difference from example 1 is (NH)₂-PEG-NH₂+ thiourea + xylylene diisocyanate): the mass ratio of vinylene carbonate is 1: 12, the other conditions were the same as in example 1. The prepared polymer electrolyte was subjected to the test method of example 1.

Example 4 preparation of gel electrolyte

The difference from example 1 is (NH)₂-PEG-NH₂+ thiourea + xylylene diisocyanate): the mass ratio of vinylene carbonate is 1: 15, other conditions were the same as in example 1. The prepared polymer electrolyte was subjected to the test method of example 1.

Example 5 preparation of gel electrolyte

The difference from example 1 is (NH)₂-PEG-NH₂+ thiourea + xylylene diisocyanate): the mass ratio of vinylene carbonate is 1: other conditions were the same as in example 1. The prepared polymer electrolyte was subjected to the test method of example 1.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.

In conclusion, the self-repairing polymer electrolyte is designed, and the self-repairing capability of the self-repairing polymer electrolyte is that the formed intermolecular reversible hydrogen bonds (the hydrogen bonds can be automatically combined under the conditions of heating, pressure, pH and the like after being broken by external force) are realized through the ureido, amino and other groups, so that the effect of reversibly repairing crack damage is achieved. The self-repairing polymer and other polymer material systems are blended to improve the mechanical property of the self-repairing polymer material, and the blended polymer can be synthesized in an in-situ polymerization mode, so that the interface impedance between an electrolyte and an interface is reduced, the solid-solid interface compatibility is improved, and the in-situ polymerization mode is simple to synthesize and is suitable for large-scale production.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.