CN115954539A - A kind of self-healing network polymer electrolyte and its preparation method and application, polymer lithium battery - Google Patents

Abstract

The invention relates to the technical field of polymer lithium batteries, in particular to a self-healing network polymer electrolyte, a preparation method and application thereof, and a polymer lithium battery. The invention provides a self-healing network polymer electrolyte, which comprises the following preparation materials in parts by mass: 3-10 parts of ionic liquid, 40-70 parts of polyethylene glycol diacrylate, disulfide diacrylate 1-10 parts of ester, 1-5 parts of crosslinking agent, 3-10 parts of chain extender, 1-5 parts of alkali, 20-30 parts of lithium salt, 1-10 parts of photoinitiator and 90-110 parts of solvent; Both the crosslinking agent and the chain extender include mercapto groups. The self-healing network polymer electrolyte has high conductivity at room temperature, stable interfacial contact and self-healing without external stimulation.

Description

A kind of self-healing network polymer electrolyte and its preparation method and application, polymer lithium battery

technical field

The invention relates to the technical field of polymer lithium batteries, in particular to a self-healing network polymer electrolyte, a preparation method and application thereof, and a polymer lithium battery.

Background technique

Wearable electronic devices such as smart bracelets and smart glasses are becoming more and more popular, however, conventional lithium batteries are difficult to be used in wearable devices due to their poor flexibility and low energy density. Therefore, researchers have extensively studied flexible solid-state lithium batteries with high energy density and good flexibility to meet consumer demand for wearable devices. As a key component of flexible lithium batteries, solid-state electrolytes are inevitably subjected to external forces such as stretching, twisting, and bending in practical applications, resulting in microcracks and fractures, which hinder the transmission of lithium ions inside the solid-state electrolyte and seriously affect the stability of the solid-state electrolyte. Battery performance and cycle performance.

Contents of the invention

The object of the present invention is to provide a kind of self-healing network polymer electrolyte and its preparation method and application, polymer lithium battery, described self-healing network polymer electrolyte has high conductivity at room temperature, interface contact is stable and does not need Self-healing can be achieved by external stimulation.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a self-healing network polymer electrolyte, which comprises the following preparation raw materials in parts by mass: 3-10 parts of ionic liquid, 40-70 parts of polyethylene glycol diacrylate, disulfide diacrylate 1-10 parts of ester, 1-5 parts of crosslinking agent, 3-10 parts of chain extender, 1-5 parts of alkali, 20-30 parts of lithium salt, 1-10 parts of photoinitiator and 90-110 parts of solvent;

Both the crosslinking agent and the chain extender include mercapto groups.

Preferably, the ionic liquid includes 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt, 1-hexyl-3-methylimidazole tetrafluoroboric acid, 1-ethyl-3-methyl Imidazole trifluoromethanesulfonate, 2,3-dimethyl-1-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide One or more of sulfonyl)imide salts and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salts.

Preferably, the disulfide diacrylate includes bis(4-vinylphenyl) disulfide and/or disulfide dimethacrylate.

Preferably, the crosslinking agent includes one of tetrakis (3-mercaptopropionate) pentaerythritol ester, hexa(3-mercaptopropionate) dipentaerythritol ester and trimethylolpropane tris (3-mercaptopropionate) or more.

Preferably, the chain extender includes 3,6-dioxa-1,8-octanedithiol, 1,8-octanedithiol, 1,10-decaneedithiol, 1,4-butane One or more of dithiol, 1,2-ethanedithiol, 1,16-hexadecanedithiol, 1,5-pentanedithiol and 1,6-hexaneedithiol;

The photoinitiator includes one or more of 2,2-dimethoxy-2-phenylacetophenone, 4-methylbenzophenone and 1-hydroxycyclohexyl phenyl ketone.

Preferably, the base includes one or more of n-butylamine, tert-butylamine, n-propylamine, tert-amylamine and isobutylamine;

The lithium salt includes one or more of LiPF ₆ , LiClO ₄ , LiTFSI, LiFSI, LiBOB and LiDFOB.

The present invention also provides a method for preparing the self-healing network polymer electrolyte described in the above technical solution, comprising the following steps:

After mixing ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, crosslinking agent, chain extender, lithium salt and solvent, mixing with photoinitiator and alkali to obtain a precursor solution;

The precursor solution is subjected to UV curing to obtain the self-healing network polymer electrolyte.

Preferably, the irradiation wavelength of the UV curing is 100-380 nm, the irradiation light intensity is 10-200 mW·cm ^-2 , and the time is 0.5-10 h.

The present invention also provides the application of the self-healing network polymer electrolyte described in the above technical solution or the self-healing network polymer prepared by the preparation method described in the above technical solution in a polymer lithium battery.

The present invention also provides a polymer lithium battery, including a positive electrode, a negative electrode, and an electrolyte. The electrolyte is the self-healing network polymer electrolyte described in the above technical solution or the self-healing polymer electrolyte prepared by the preparation method described in the above technical solution. networked polymers.

The invention provides a self-healing network polymer electrolyte, which comprises the following preparation raw materials in parts by mass: 3-10 parts of ionic liquid, 40-70 parts of polyethylene glycol diacrylate, disulfide diacrylate 1-10 parts of ester, 1-5 parts of crosslinking agent, 3-10 parts of chain extender, 1-5 parts of alkali, 20-30 parts of lithium salt, 1-10 parts of photoinitiator and 90-110 parts of solvent; Both the crosslinking agent and the chain extender include mercapto groups. A thiol-ene click reaction will occur between the carbon-carbon double bond in the disulfide diacrylate and polyethylene glycol diacrylate and the mercapto group of the cross-linking agent and chain extender, making the self-healing network The polymer electrolyte has a disulfide bond network structure, and the dynamic disulfide bonds can make the electrolyte membrane self-heal at room temperature without external stimulation. The ionic liquid has good ion transport and flame retardancy, not only accelerates the transmission of lithium ions but also has good flame retardancy, and improves the conductivity of the electrolyte membrane at room temperature without reducing the mechanical properties of the membrane and the electrolyte The good interfacial compatibility between the film and the lithium metal negative electrode reduces the impedance of the interface, thereby improving the cycle performance and rate performance of the battery. According to the description of the examples, the ionic conductivity of the self-healing network polymer electrolyte of the present invention reaches 1.13×10 ^-4 S·cm ^-1 at room temperature; the self-healing network polymer electrolyte is used as the electrolyte The assembled lithium iron phosphate battery has a specific discharge capacity of 160mAh·g ^-1 at a rate of 0.1C.

The present invention also provides a preparation method of the self-healing network polymer electrolyte described in the technical solution, comprising the following steps: mixing ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, crosslinking agent, After the chain agent, lithium salt and solvent are mixed, they are mixed with photoinitiator and alkali to obtain a precursor solution; the precursor solution is subjected to UV curing to obtain the self-healing network polymer electrolyte. The UV curing can promote the occurrence of thiol-ene click reaction; meanwhile, the preparation method has simple operation, mild conditions and low cost.

Description of drawings

Fig. 1 is the self-healing network polymer electrolyte obtained in Example 1, tetrakis (3-mercaptopropionate) pentaerythritol ester, polyethylene glycol diacrylate, diphenyl disulfide bis (2-methacrylamide) and 3,6-dioxa-1,8-infrared spectrograms of octane dithiol;

Fig. 2 is the physical picture and the SEM figure of the self-healing network polymer electrolyte prepared in Example 1;

Fig. 3 is the ionic conductivity of the self-healing reticulated polymer electrolyte membrane prepared in Example 1 and the self-healing reticulated polymer electrolyte membrane after standing for 24 hours as a function of temperature;

Fig. 4 is that the self-healing reticular polymer electrolyte prepared in embodiment 1 is the room temperature cycle test diagram of the button battery assembled by electrolyte;

Fig. 5 is the cycle test diagram of the room temperature rate of button cell described in embodiment 1;

Fig. 6 is the cycle stability curve of the Li//Li symmetric button battery assembled by the self-healing network polymer electrolyte prepared in Example 1;

Fig. 7 is the self-healing process of the self-healing network polymer electrolyte membrane prepared in Example 1 at room temperature;

Fig. 8 is the flame retardant process of the self-healing network polymer electrolyte membrane prepared in Example 1.

Detailed ways

The invention provides a self-healing network polymer electrolyte, which comprises the following preparation raw materials in parts by mass: 3-10 parts of ionic liquid, 40-70 parts of polyethylene glycol diacrylate, disulfide diacrylate 1-10 parts of ester, 1-5 parts of crosslinking agent, 3-10 parts of chain extender, 1-5 parts of alkali, 20-30 parts of lithium salt, 1-10 parts of photoinitiator and 90-110 parts of solvent;

Both the crosslinking agent and the chain extender include mercapto groups.

In the present invention, unless otherwise specified, all preparation materials are commercially available products well known to those skilled in the art.

In terms of parts by mass, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 3-10 parts of ionic liquid, preferably 4-8 parts, more preferably 5-6 parts. In the present invention, the ionic liquid preferably includes 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt, 1-hexyl-3-methylimidazolium tetrafluoroboric acid, 1-ethyl-3 -Methylimidazolium trifluoromethanesulfonate, 2,3-dimethyl-1-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidine bis( One or more of trifluoromethanesulfonyl)imide salt and 1-octyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt; more preferably 1-ethyl-3-methane imidazole bistrifluoromethanesulfonimide salt; when the ionic liquid is more than two of the above-mentioned specific selections, the present invention does not have any special restrictions on the proportioning of the above-mentioned specific substances, and it can be mixed according to any proportioning. Can.

In the present invention, the ionic liquid not only accelerates the transmission of lithium ions but also has good flame retardancy, improves the conductivity of the electrolyte membrane at room temperature without reducing the mechanical properties of the membrane, and the electrolyte membrane and the lithium metal negative electrode are good The interfacial compatibility reduces the impedance of the interface, thereby improving the cycle performance and rate performance of the battery.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 40-70 parts of polyethylene glycol diacrylate, preferably 45-65 parts, more preferably 50-60 copies. In the present invention, the molecular weight of the polyethylene glycol diacrylate is preferably 400-4000 g/mol, more preferably 1000-3000 g/mol. In the present invention, the role of polyethylene glycol diacrylate is to transport lithium ions and improve the mechanical properties of self-healing network polymer electrolysis.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 1 to 10 parts of disulfide diacrylate, preferably 2 to 8 parts, more preferably 4 to 6 servings. In the present invention, the disulfide diacrylate preferably includes bis(4-vinylphenyl) disulfide and/or disulfide dimethacrylate, more preferably disulfide dimethacrylate .

In the present invention, the preparation method of the disulfide dimethacrylate preferably comprises the following steps:

In a nitrogen atmosphere, disulfide, isocyanoethyl methacrylate and an organic solvent are mixed and reacted to obtain the disulfide dimethacrylate.

In the present invention, the nitrogen atmosphere is preferably achieved by bubbling nitrogen.

In the present invention, the disulfide preferably includes 4,4-diaminodiphenyl disulfide, bis(4-hydroxyphenyl) disulfide and bis(2-hydroxyethyl) disulfide and bis( One or more of 2-diaminoethyl) disulfides; when the disulfides are two or more of the above-mentioned specific selections, the present invention does not have any special restrictions on the proportioning of the above-mentioned specific substances, It can be mixed according to any proportion. In the present invention, the organic solvent preferably includes one or more of benzene, toluene, methylene chloride, methanol, ethanol, acetone, acetonitrile, dimethylsulfoxide and N,N-dimethylformamide; When the organic solvent is two or more of the above-mentioned specific options, the present invention does not have any special limitation on the proportion of the above-mentioned specific substances, and they can be mixed according to any proportion. In the present invention, when the disulfide is 4,4-diaminodiphenyl disulfide, bis(2-diaminoethyl) disulfide, the reaction does not need to add a catalyst; when the disulfide When sulfide is two (4-hydroxyphenyl) disulfides, two (2-hydroxyethyl) disulfides, the reaction needs to add a catalyzer, and the catalyzer is preferably dibutyltin dilaurate; The volume ratio of the mass of ether to the dibutyltin dilaurate is 2.5g:1mL or 0.31g:0.2mL.

In the present invention, the mass ratio of disulfide, isocyanoethyl methacrylate and organic solvent is preferably (3-10):(5-10):(5-15).

The present invention does not have any special limitation on the mixing, and it is sufficient to adopt a process well known to those skilled in the art and ensure that the disulfide and isocyanoethyl methacrylate can be fully dissolved in the organic solvent.

In the present invention, the reaction temperature is preferably 20-80°C, more preferably 30-60°C, most preferably 40-50°C; the reaction time is preferably 10-30 hours, more preferably 15-25 hours. In the present invention, the reaction is preferably carried out under stirring conditions. The present invention does not have any special limitation on the stirring conditions, and the conditions well known to those skilled in the art can be used.

In the present invention, the function of the disulfide diacrylate is that the dynamic disulfide bonds it contains can make the electrolyte membrane self-healing at room temperature without external stimulation.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 1 to 5 parts of crosslinking agent, preferably 2 to 4 parts, more preferably 2.5 to 3.5 parts . In the present invention, the crosslinking agent preferably includes tetrakis (3-mercaptopropionate) pentaerythritol ester, hexa(3-mercaptopropionate) dipentaerythritol ester and trimethylolpropane tris (3-mercaptopropionate) One or more of them; when the cross-linking agent is two or more of the above-mentioned specific selections, the present invention does not have any special limitation on the proportion of the above-mentioned specific substances, and can be mixed according to any proportion.

In the present invention, the function of the cross-linking agent is to generate a thiol-ene click reaction between the carbon-carbon double bond of disulfide diacrylate and polyethylene glycol diacrylate and the mercapto group of the cross-linking agent. Self-healing network polymers, thereby improving the mechanical properties of the polymer.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 3 to 10 parts of chain extenders, preferably 4 to 8 parts, more preferably 5 to 6 parts . In the present invention, the chain extender preferably includes 3,6-dioxa-1,8-octanedithiol, 1,8-octanedithiol, 1,10-decaneedithiol, 1, One or more of 4-butanedithiol, 1,2-ethanedithiol, 1,16-hexadecanedithiol, 1,5-pentanedithiol and 1,6-hexanedithiol ; When the chain extender is two or more of the above-mentioned specific selections, the present invention does not have any special limitation on the proportion of the above-mentioned specific substances, and it can be mixed according to any proportion.

In the present invention, the effect of the chain extender is that a thiol-ene click reaction occurs between the carbon-carbon double bond of disulfide diacrylate and polyethylene glycol diacrylate and the mercapto group of the chain extender, so that Disulfide diacrylate and polyethylene glycol diacrylate are polymerized with chain extenders to increase the length of molecular segments, thereby improving the flexibility of the polymer.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 1-5 parts of alkali, preferably 2-5 parts, more preferably 3-4 parts. In the present invention, the base preferably includes one or more of n-butylamine, tert-butylamine, n-propylamine, tert-amylamine and isobutylamine; when the base is two or more of the above-mentioned specific options, the present invention The invention does not have any special limitation on the proportion of the above-mentioned specific substances, and they can be mixed according to any proportion.

In the present invention, the function of the base is to accelerate the reaction between the carbon-carbon double bond and the mercapto group.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 20-30 parts of lithium salt, preferably 22-28 parts, more preferably 23-26 parts. In the present invention, the lithium salt preferably includes one or more of LiPF ₆ , LiClO ₄ , LiTFSI, LiFSI, LiBOB and LiDFOB; when the lithium salt is two or more of the above specific options, the present invention There is no special limitation on the proportion of the above-mentioned specific substances, and they can be mixed according to any proportion.

In the present invention, the role of the lithium salt is to provide lithium ions and lower the glass transition temperature of the polymer electrolyte.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 1 to 10 parts of photoinitiator, preferably 2 to 8 parts, more preferably 3 to 6 parts . In the present invention, the photoinitiator preferably includes one of 2,2-dimethoxy-2-phenylacetophenone, 4-methylbenzophenone and 1-hydroxycyclohexyl phenyl ketone One or more; when the photoinitiator is two or more of the above-mentioned specific selections, the present invention does not have any special limitation on the proportion of the above-mentioned specific substances, and it can be mixed according to any proportion.

Based on the mass fraction of the ionic liquid, the raw materials for the electrolysis of the self-healing network polymer in the present invention include 90-110 parts of solvent, preferably 95-105 parts, more preferably 98-102 parts. In the present invention, the solvent is preferably anhydrous acetonitrile.

In the present invention, the shape of the self-healing network polymer electrolyte is preferably a self-healing network polymer electrolyte membrane, and the thickness of the self-healing network polymer electrolyte membrane is preferably 100-120 μm.

The present invention also provides a method for preparing the self-healing network polymer electrolyte described in the above technical solution, comprising the following steps:

After mixing ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, crosslinking agent, chain extender, lithium salt and solvent, mixing with photoinitiator and alkali to obtain a precursor solution;

The precursor solution is subjected to UV curing to obtain the self-healing network polymer electrolyte.

After mixing ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, cross-linking agent, chain extender, lithium salt and solvent, and mixing with photoinitiator and alkali, the precursor solution is obtained.

In the present invention, the mixing of the ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, crosslinking agent, chain extender, lithium salt and solvent is preferably carried out under stirring conditions; the stirring The time for stirring is preferably 5 to 12 hours. The present invention does not have any special limitation on the stirring speed. A rotating speed well known to those skilled in the art is adopted to ensure that the ionic liquid, polyethylene glycol diacrylate, diacrylate The thioether diacrylate, the crosslinking agent, the chain extender and the lithium salt are fully dissolved in the solvent.

In the present invention, the mixing with the photoinitiator and alkali is preferably carried out under stirring conditions; the stirring time is preferably 2 to 5 hours, and the present invention does not have any special restrictions on the stirring speed. The rotating speed well-known to those skilled in the art and ensuring that the photoinitiator and the base are fully dissolved in the solvent under the above-mentioned stirring time are sufficient.

After obtaining the precursor solution, the present invention performs UV curing on the precursor solution to obtain the self-healing network polymer electrolyte.

After the precursor solution is obtained, the present invention also preferably ultrasonicates the precursor solution for 1 to 10 minutes; the present invention does not have any special limitation on the conditions of the ultrasonic, and the conditions well known to those skilled in the art can be used.

After the ultrasonic treatment is completed, the present invention preferably further includes scraping the precursor solution on the surface of the polytetrafluoroethylene plate, and then performing pre-curing. In the present invention, the doctor blade with 750 μm grooves is preferably used for the scraping coating; the pre-curing method is preferably drying, and the drying temperature is preferably 20-40° C., and the drying time is preferably 20-40 hours.

In the present invention, the UV curing irradiation wavelength is preferably 100-380 nm, more preferably 300-380 nm; the irradiation light intensity is preferably 10-200 mW·cm ^-2 , more preferably 100-200 mW·cm ^-2 ; time Preferably it is 0.5-10 h, more preferably 0.5-1.5 h.

After the UV curing is completed, the present invention preferably also includes vacuum drying; the present invention does not have any special limitation on the vacuum drying process, and it can be carried out by a process well known to those skilled in the art. After the vacuum drying is completed, the present invention preferably includes peeling off the film; the present invention does not have any special limitation on the process of peeling off the film, and it can be carried out by a process well known to those skilled in the art.

The present invention also provides the application of the self-healing network polymer electrolyte described in the above technical solution or the self-healing network polymer prepared by the preparation method described in the above technical solution in a polymer lithium battery.

The present invention also provides a polymer lithium battery, including a positive electrode, a negative electrode and an electrolyte, characterized in that the electrolyte is the self-healing network polymer electrolyte described in the above technical solution or prepared by the preparation method described in the above technical solution The resulting self-healing network polymer.

The present invention has no special requirements on the positive and negative electrodes, and the positive and negative electrodes for lithium electrodes well known to those skilled in the art can be used. In a specific embodiment of the present invention, the positive electrode includes a positive electrode active material, a current collector, a conductive agent and a binder, and the mass ratio of the positive electrode active material, conductive agent and binder is preferably 8:1:1; The positive electrode active material includes one or more of lithium cobaltate, lithium manganate, lithium iron phosphate and lithium iron manganese phosphate; the current collector preferably includes copper foil or aluminum foil; the conductive agent preferably includes acetylene black, One or more of piano black and carbon nanotubes; the binder preferably includes one or more of polytetrafluoroethylene, polyurethane and polyvinylidene fluoride. In the present invention, the negative electrode is preferably lithium metal. The present invention has no special requirements on the assembling method of the polymer lithium battery, and the assembling method known to those skilled in the art can be adopted.

The polymer lithium battery provided by the invention uses the self-healing network polymer electrolyte as an electrolyte, and has excellent rate performance.

The self-healing network polymer electrolyte provided by the present invention, its preparation method and application, and the polymer lithium battery are described in detail below in conjunction with the examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

Dissolve 2.5g of 4,4-diaminodiphenyl disulfide in acetone, add 2.9 mL of isocyanoethyl methacrylate after bubbling nitrogen for 30 min, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2- methacrylamide);

0.55g lithium salt (LiTFSI), 0.08g ionic liquid (1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt), 1.25g molecular weight 1000g/mol polyethylene glycol diacrylate, 0.077 g diphenyl disulfide bis(2-methacrylamide), 0.0305 g tetrakis(3-mercaptopropionic acid) pentaerythritol ester and 0.23 g 3,6-dioxa-1,8-octanedithiol dissolved in Stir in water acetonitrile for 12 hours. After stirring evenly, add 20 mg of photoinitiator and 10 μL of n-butylamine and continue stirring for 1 hour to obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4h after curing, and peeled off the film, obtained from the healing network polymer electrolyte;

Fig. 1 is the self-healing network polymer electrolyte obtained in Example 1, tetrakis (3-mercaptopropionate) pentaerythritol ester, polyethylene glycol diacrylate, diphenyl disulfide bis (2-methacrylamide) And the infrared spectrogram of 3,6-dioxa-1,8-octanedithiol, the 2560cm ^-1 absorption band V _SH peak and the 1620cm ^-1 absorption band V _C=C disappear in the said infrared spectrum, indicating Tetrakis(3-mercaptopropionic acid)pentaerythritol ester, polyethylene glycol diacrylate, diphenyl disulfide bis(2-methacrylamide) and 3,6-dioxa-1,8-octane disulfide Alcohol undergoes a thiol-ene click reaction to form a network polymer;

Figure 2 is the physical picture and SEM picture of the self-healing network polymer electrolyte prepared in Example 1, where (a) is a photo of the electrolyte folded in half, (b) is a photo of the electrolyte tiled, and (c) is self-healing The SEM image of the healed network polymer electrolyte; as can be seen from Figure 2, the self-healing network polymer electrolyte prepared in Example 1 is a transparent self-supporting electrolyte membrane, and can be restored after being folded and rolled up, the overall appearance It shows that the electrolyte membrane has excellent mechanical flexibility, and the microscopic appearance is dense and non-porous; it is beneficial to the interface contact with the electrode;

Figure 3 is a graph showing the ionic conductivity of the self-healing network polymer electrolyte membrane prepared in Example 1 and the self-healing network polymer electrolyte membrane after standing for 24 hours to self-heal with temperature, and the film thickness is about 110 μm , the original ionic conductivity at 28°C was 1.13×10 ^-4 S·cm ^-1 , and the ionic conductivity of the self-healing self-healing network polymer electrolyte membrane was 0.569×10 ^-4 S·cm ^-1 . The ionic conductivity of the self-healing network polymer electrolyte membrane after self-healing is slightly lower than the original ionic conductivity;

The self-healing reticular polymer electrolyte prepared in Example 1 is used as the electrolyte to assemble a button battery, the positive electrode active material is lithium iron phosphate, the current collector is aluminum foil, the conductive agent is acetylene black, and the binder is polytetrafluoroethylene; Extremely metallic lithium. Figure 4 is the cycle test diagram of the button battery at room temperature. From Figure 4, it can be seen that the original and self-healing self-healing network polymer electrolytically assembled the button battery. At 0.1C rate, the original self-healing network The initial discharge capacity of the battery with polymer electrolyte is 146.9mAh·g ^-1 , and it maintains 161mAh·g ^-1 after 19 cycles, and the Coulombic efficiency is 99.8%. After self-healing, the self-healing network polymer electrolytically assembled battery exhibited an initial discharge capacity of 140.9 mAh g ^-1 and maintained 161 mAh g ^-1 after 19 cycles, with a Coulombic efficiency of 99.9%, which was comparable to that of the pristine battery ( 146.9mAh·g ^-1 ) is very close, and the specific capacity reaches 161mAh·g ^-1 after 19 cycles. However, the self-healing self-healing network polymer electrolytically assembled battery exhibited a higher discharge specific capacity than the original battery after 11 cycles, indicating that the repaired electrolyte membrane can still be effectively applied to lithium-ion batteries;

Fig. 5 is the room temperature rate cycle test diagram of the button cell, as can be seen from Fig. 5, at room temperature, the discharge specific capacity of lithium iron phosphate under 0.1C rate is 160mAh g ^-1 ; The discharge specific capacity is 150mAh·g ^-1 ; the discharge specific capacity at 0.5C rate is 130mAh·g ^-1 ; the discharge specific capacity at 1C rate is 100mAh·g ^-1 , and the ratio of lithium iron phosphate at 2C rate The capacity is 80mAh·g ^-1 , and when the current rate returns to the original 0.1C, the specific discharge capacity is almost completely recovered. It can be seen that the resulting coin cell has excellent rate performance;

6 is a cycle stability curve of a Li//Li symmetric coin cell assembled with a self-healing network polymer electrolyte prepared in Example 1. Using a lithium foil with a diameter of 12 mm, the symmetric cell was cycled under one-hour Li ⁺ plating and one-hour Li ⁺ stripping at a current density of 0.05 mA cm ^-2 , with negative and positive voltages representing Li-ion plating and Li-stripping, respectively. ion. After cycling for 120 hours, the positive voltage is still constant at 0.15V, indicating that the interface between the Li anode and the electrolyte membrane is relatively stable and it has excellent interfacial compatibility with the Li anode;

FIG. 7 shows the self-healing process of the self-healing network polymer electrolyte membrane prepared in Example 1 at room temperature. The thickness of the electrolyte membrane is about 800 μm, and the use of a thicker membrane aims to improve the operability of the self-healing test. Cut the film into two pieces with a scalpel, make the two separated parts contact, and after standing for 24 hours, the cut film heals. Although the gap has not completely disappeared, the healed film can bear the weight of 100g without breaking. Exhibits good self-healing properties, which are attributed to the urea groups and dynamic disulfide bonds in the polymer;

Fig. 8 is the flame retardant process of the self-healing network polymer electrolyte membrane prepared in Example 1. When there is no igniter after the burning film, no further burning is observed, and the flame will extinguish itself, which has good flame retardancy.

Example 2

The preparation of self-healing network polymer electrolyte, the steps are as follows:

Dissolve 2.5g of bis(4-hydroxyphenyl)disulfide in dichloromethane, heat and stir at 60°C for 30min after bubbling nitrogen for 30min, add 1mL of dibutyltin dilaurate and 2.9mL of methyl Acrylate isocyanoethyl ester, stirred at 40°C for 20 hours to obtain diphenyl disulfide bis(2-methacrylate);

0.55g lithium salt (LiTFSI), 0.08g ionic liquid (1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt), 1.25g molecular weight 1000g/mol polyethylene glycol diacrylate, 0.077 g diphenyl disulfide bis(2-methacrylate), 0.0305 g tetrakis(3-mercaptopropionic acid) pentaerythritol ester and 0.23 g 3,6-dioxa-1,8-octanedithiol dissolved in Stir in water acetonitrile for 12 hours. After stirring evenly, add 20 mg of photoinitiator and 10 μL of n-butylamine and continue stirring for 1 hour to obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4 hours after curing, and peeled off the film to obtain a healed network polymer electrolyte.

The room temperature conductivity of the self-healing network polymer electrolyte prepared in Example 2 was 8.76×10 ^-5 S·cm ^-1 .

Example 3

The preparation of self-healing network polymer electrolyte, the steps are as follows:

Dissolve 0.31g of bis(2-hydroxyethyl)disulfide in dichloromethane, heat and stir at 60°C for 30min after bubbling nitrogen gas for 30min, add 0.2mL dibutyltin dilaurate and 0.58mL Isocyanoethyl methacrylate, stirred at 40°C for 20 hours to obtain disulfide bis(2-methacrylate);

0.55g lithium salt (LiTFSI), 0.08g ionic liquid (1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt), 1.25g molecular weight 1000g/mol polyethylene glycol diacrylate, 0.077 g disulfide bis(2-methacrylate), 0.0305 g tetrakis(3-mercaptopropionate) pentaerythritol ester and 0.23 g 3,6-dioxa-1,8-octanedithiol dissolved in anhydrous acetonitrile Stir in medium for 12h, after stirring evenly, add 20mg photoinitiator and 10μL n-butylamine and continue stirring for 1h to obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4 hours after curing, and peeled off the film to obtain a healed network polymer electrolyte.

The room temperature conductivity of the self-healing network polymer electrolyte prepared in Example 3 was 8.56×10 ^-5 S·cm ^-1 .

Example 4

The preparation of self-healing network polymer electrolyte, the steps are as follows:

Dissolve 2.5g of 4,4-diaminodiphenyl disulfide in acetone, add 2.9mL isocyanoethyl methacrylate after bubbling nitrogen gas for 30min, and stir at room temperature for 20h to obtain diphenyl disulfide bis(2 -methacrylamide);

0.6063g lithium salt (LiTFSI), 0.1586g ionic liquid (1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt), 1.25g molecular weight 1000g/mol polyethylene glycol diacrylate, 0.077 g diphenyl disulfide bis(2-methacrylamide), 0.0305 g tetrakis(3-mercaptopropionic acid) pentaerythritol ester and 0.23 g 3,6-dioxa-1,8-octanedithiol dissolved in Stir in water acetonitrile for 12 hours. After stirring evenly, add 20 mg of photoinitiator and 10 μL of n-butylamine and continue stirring for 1 hour to obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4 hours after curing, and peeled off the film to obtain a healed network polymer electrolyte.

The room temperature conductivity of the self-healing network polymer electrolyte prepared in Example 4 was 1.24×10 ^-4 S·cm ^-1 .

Example 5

The preparation of self-healing network polymer electrolyte, the steps are as follows:

Dissolve 2.5g of 4,4-diaminodiphenyl disulfide in acetone, add 2.9 mL of isocyanoethyl methacrylate after bubbling nitrogen for 30 min, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2- methacrylamide);

0.6650g lithium salt (LiTFSI), 0.2379g ionic liquid (1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt), 1.25g molecular weight 1000g/mol polyethylene glycol diacrylate, 0.077 g diphenyl disulfide bis(2-methacrylamide), 0.0305 g tetrakis(3-mercaptopropionic acid) pentaerythritol ester and 0.23 g 3,6-dioxa-1,8-octanedithiol dissolved in Stir in water acetonitrile for 12 hours. After stirring evenly, add 20 mg of photoinitiator and 10 μL of n-butylamine and continue stirring for 1 hour to obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4 hours after curing, and peeled off the film to obtain a healed network polymer electrolyte.

The room temperature conductivity of the self-healing network polymer electrolyte prepared in Example 5 was 1.31×10 ^-4 S·cm ^-1 .

Comparative example 1

The preparation of self-healing network polymer electrolyte, the steps are as follows:

Dissolve 2.5g of 4,4-diaminodiphenyl disulfide in acetone, add 2.9 mL of methacrylate isocyanate after bubbling nitrogen for 30 min, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2-methyl base acrylamide);

0.489g lithium salt (LiTFSI), 1.25g polyethylene glycol diacrylate with a molecular weight of 1000g/mol, 0.077g diphenyl disulfide bis(2-methacrylamide), 0.0305g tetrakis(3-mercaptopropionic acid) Dissolve pentaerythritol ester and 0.23g of 3,6-dioxa-1,8-octanedithiol in anhydrous acetonitrile and stir for 12h. After stirring evenly, add 20mg of photoinitiator and 10μL of n-butylamine and continue to stir for 1h. Obtain a uniform precursor solution;

The homogeneous precursor solution was ultrasonicated for 3 minutes, and the resulting slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene board, pre-cured in a desiccator for 24 hours, and then irradiated with ultraviolet light for 1 hour (wavelength: 365 nm, light intensity: 150mW·cm ^-2 ), dried in a vacuum oven at 60°C for 4 hours after curing, and peeled off the film to obtain a healed network polymer electrolyte.

The room temperature conductivity of the self-healing network polymer electrolyte prepared in Comparative Example 1 was 9.7×10 ^-5 S·cm ^-1 .

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A self-healing network polymer electrolyte, characterized in that, in parts by mass, it comprises the following preparation raw materials: 3-10 parts of ionic liquid, 40-70 parts of polyethylene glycol diacrylate, disulfide 1-10 parts of diacrylate, 1-5 parts of crosslinking agent, 3-10 parts of chain extender, 1-5 parts of alkali, 20-30 parts of lithium salt, 1-10 parts of photoinitiator and 90-110 parts of solvent ; Both the crosslinking agent and the chain extender include mercapto groups. 2. The self-healing network polymer electrolyte according to claim 1, wherein the ionic liquid comprises 1-ethyl-3-methylimidazole bis-trifluoromethanesulfonimide salt, 1-hexyl -3-methylimidazolium tetrafluoroboric acid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 2,3-dimethyl-1-propylimidazolium bis(trifluoromethanesulfonyl)yl One of imine, 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide salt and 1-octyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt one or more species. 3. The self-healing network polymer electrolyte according to claim 1, wherein the disulfide diacrylate comprises bis(4-vinylphenyl) disulfide and/or disulfide diacrylate Methacrylate. 4. The self-healing network polymer electrolyte according to claim 1, wherein the crosslinking agent comprises tetrakis (3-mercaptopropionate) pentaerythritol ester, six (3-mercaptopropionate) dipentaerythritol ester and one or more of trimethylolpropane tris(3-mercaptopropionate). 5. The self-healing network polymer electrolyte of claim 1, wherein the chain extender comprises 3,6-dioxa-1,8-octanedithiol, 1,8- Octanedithiol, 1,10-decanedithiol, 1,4-butanedithiol, 1,2-ethanedithiol, 1,16-hexadecanedithiol, 1,5-pentanedithiol One or more of alcohol and 1,6-hexanedithiol; The photoinitiator includes one or more of 2,2-dimethoxy-2-phenylacetophenone, 4-methylbenzophenone and 1-hydroxycyclohexyl phenyl ketone. 6. The self-healing network polymer electrolyte according to claim 1, wherein the base comprises one or more of n-butylamine, tert-butylamine, n-propylamine, tert-amylamine and isobutylamine; The lithium salt includes one or more of LiPF ₆ , LiClO ₄ , LiTFSI, LiFSI, LiBOB and LiDFOB. 7. The method for preparing the self-healing network polymer electrolyte according to any one of claims 1 to 6, characterized in that it comprises the following steps: After mixing ionic liquid, polyethylene glycol diacrylate, disulfide diacrylate, crosslinking agent, chain extender, lithium salt and solvent, mixing with photoinitiator and alkali to obtain a precursor solution; The precursor solution is subjected to UV curing to obtain the self-healing network polymer electrolyte. 8 . The preparation method according to claim 7 , wherein the irradiation wavelength of the UV curing is 100-380 nm, the irradiation light intensity is 10-200 mW·cm ^-2 , and the irradiation time is 0.5-10 h. 9. The application of the self-healing network polymer electrolyte according to any one of claims 1 to 6 or the self-healing network polymer prepared by the preparation method described in claim 7 or 8 in polymer lithium batteries. 10. A polymer lithium battery, comprising a positive pole, a negative pole and an electrolyte, characterized in that the electrolyte is the self-healing network polymer electrolyte according to any one of claims 1 to 6 or any one of claims 7 or 8 The self-healing network polymer prepared by the preparation method.

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