CN110994020B - A kind of bifunctional self-healing polymer electrolyte and preparation method thereof - Google Patents

Abstract

The invention discloses a bifunctional self-healing polymer electrolyte, comprising polyethylene glycol with double bonds, a cross-linking agent with disulfide bonds, an initiator and a chain transfer agent; Crosslinkers have both disulfide and hydrogen bonds. The present invention also provides a method for preparing a bifunctional self-healing polymer electrolyte, comprising the following steps: S1: reacting a monomer with a double bond and a monomer with a disulfide bond in a first solution to obtain a monomer with a disulfide bond Sulfur-bonded cross-linking agent; S2: Dissolve the disulfide-bonded cross-linking agent and the double-bonded polyethylene glycol in a second solvent, add an initiator and a chain transfer agent, and after deoxygenation, heat Reaction to obtain a PEG-SS copolymer; S3: dissolving the PEG-SS copolymer in a third solvent, adding a lithium salt and stirring evenly, casting the mixed solution to form a film, and drying to obtain the bifunctional self-healing polymerization material electrolyte. The crosslinking agent with disulfide bond of the present invention has both disulfide bond and hydrogen bond, and realizes self-healing of electrolyte material at room temperature.

Description

A kind of bifunctional self-healing polymer electrolyte and preparation method thereof

technical field

The invention belongs to the technical field of polymer electrolytes, and more particularly, relates to a bifunctional self-healing polymer electrolyte and a preparation method thereof.

Background technique

Since the first commercial release of lithium-ion batteries at the end of the 20th century, they have developed rapidly in the past two decades. It is widely used in daily electronic devices such as computers and mobile phones due to its high energy density and low discharge rate. However, the traditional lithium-ion battery will cause damage and damage to the electrode and the electrolyte during collision and bending due to external force, which will seriously affect the electrochemical performance of the battery itself, and even cause great safety hazards. Therefore, replacing liquid electrolytes with solid electrolytes and introducing self-healing functions can effectively solve a series of potential safety hazards brought by liquid electrolytes and prolong the service life of lithium-ion batteries.

Introducing dynamic cross-linking of hydrogen bonds into polymers can achieve excellent mechanical properties and self-healing effects. The introduction of hydrogen bonds can make the polymer re-form hydrogen bonds through its own interfacial functional groups when it is broken and damaged, so as to achieve rapid self-healing function. However, the function of the hydrogen bonding system at room temperature is difficult to achieve, because the bonding force at room temperature is weak, and the effect of hydrogen bonding will be destroyed at high temperature, so it will make the mechanical properties of the polymer electrolyte and self. The ability to heal is severely compromised, resulting in the performance of lithium-ion batteries not being as good as before.

SUMMARY OF THE INVENTION

In view of the above defects or improvement needs of the prior art, the present invention provides the introduction of disulfide bonds into polymers, and the crosslinking agent with disulfide bonds has both disulfide bonds and hydrogen bonds, so as to realize self-healing of electrolyte materials at room temperature.

In order to achieve the above object, the present invention provides a bifunctional self-healing polymer electrolyte, the bifunctional self-healing polymer electrolyte comprises polyethylene glycol with double bonds, crosslinking agent with disulfide bonds, and initiator and a chain transfer reagent; wherein, the cross-linking agent with disulfide bonds has both disulfide bonds and hydrogen bonds, and the disulfide bonds and hydrogen bonds have self-healing functions.

Further, the disulfide bond is self-healing through a dynamic exchange reaction, and the structural formula of the dynamic exchange reaction is as follows:

According to another aspect of the present invention, there is provided a method for preparing the bifunctional self-healing polymer electrolyte, comprising the steps of:

S1: react the monomer with a double bond and the monomer with a disulfide bond in the first solution, and obtain a crosslinking agent with a disulfide bond through a nucleophilic addition reaction;

S2: Dissolve the cross-linking agent with disulfide bonds and the polyethylene glycol with double bonds obtained in S1 in a second solvent, add an initiator and a chain transfer reagent, and after deoxygenation, heating and reacting to obtain PEG -SS copolymer;

S3: Dissolving the PEG-SS copolymer obtained in S2 in a third solvent, adding lithium salt and stirring evenly, casting the mixed solution to form a film, and drying to obtain the bifunctional self-healing polymer electrolyte.

Further, in step S1, the monomer with double bond is 2-isocyanoethyl acrylate or isocyanoethyl methacrylate, and the molecular structural formula is respectively:

Further, in step S1, the monomer with disulfide bond is cystamine dihydrochloride, bis(2-hydroxyethyl) disulfide, 4,4'-diaminodiphenyl disulfide, 4, One or more of 4'-dihydroxydiphenyl disulfide, the molecular structural formulas are:

Further, in step S1, the molar ratio of the monomer with a double bond and the monomer with a disulfide bond is 1:6˜1:2.

Further, in step S2, the polyethylene glycol with double bond is methoxy polyethylene glycol acrylate PEGA or polyethylene glycol methyl ether methacrylate PEGMA, and the structural formula is respectively:

Among them, n=7-45.

Further, in step S2, the molar ratio of the polyethylene glycol with double bonds and the crosslinking agent with disulfide bonds is 100:(10-40).

Further, in step S3, the lithium salt is selected from one or more of lithium perchlorate, lithium bistrifluoromethylsulfonimide, lithium bisfluorosulfonimide, lithium tetrafluoroborate, and lithium hexafluorophosphate ; The molar ratio of the ethylene oxide EO segment in the lithium salt and the PEG-SS copolymer is 1:8 to 1:25.

Further, the first solvent, the second solvent and the third solvent are all one or more of tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone.

In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

(1) In the bifunctional self-healing polymer electrolyte of the present invention, disulfide bonds are introduced into the polymer, and the crosslinking agent with disulfide bonds has both disulfide bonds and hydrogen bonds. On the one hand, the bond energy of disulfide bonds is relatively low Low and it can perform reversible exchange dynamic equilibrium reaction under mild conditions, on the other hand, without external stimulation, the translocation of disulfide can also occur, realizing self-healing of electrolyte materials at room temperature.

(2) The bifunctional self-healing polymer electrolyte of the present invention not only solves the battery damage caused by collision or bending of the lithium ion battery, but also enables the lithium ion battery to self-heal at room temperature without external stimulation.

(3) In the preparation method of the bifunctional self-healing polymer electrolyte of the present invention, the prepared cross-linking agent with disulfide bond is cross-linked with PEGA or PEGMA to obtain a PEG-SS copolymer. Compared with the existing technology, the self-healing effect of the copolymer PEG-SS is better, and the mechanical properties, self-healing effect and electrochemical performance of the polymer electrolyte are improved.

(4) In the preparation method of the bifunctional self-healing polymer electrolyte of the present invention, PEGA or PEGMA with different molecular weights are selected to react with different cross-linking agents with disulfide bonds, and then these prepolymers with different molecular weights are reacted with Cross-linking agents with different structures of disulfide bonds are cross-linked to form a polymer cross-linked network, and then by optimizing the molar ratio between substances, reaction temperature, and reaction time in the reaction process, on the one hand, the reactivity is maximized, and on the other hand, the reaction activity is maximized. The maximum yield of each reaction was achieved.

Description of drawings

FIG. 1 is a graph showing the variation of electrical conductivity with temperature of the bifunctional self-healing polymer electrolyte film involved in Example 1 of the present invention;

Fig. 2 is the electrochemical stability window diagram of the bifunctional self-healing polymer electrolyte film involved in Example 1 of the present invention;

3 is a battery cycle performance diagram of the bifunctional self-healing polymer electrolyte film involved in Example 1 of the present invention;

Fig. 4 is a self-healing process diagram of the bifunctional self-healing polymer electrolyte film involved in Example 1 of the present invention after being cut.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The invention provides a bifunctional self-healing polymer electrolyte, which is characterized in that the bifunctional self-healing polymer electrolyte comprises polyethylene glycol with double bond, crosslinking agent with disulfide bond, initiator and chain transfer Reagent; wherein, the cross-linking agent with disulfide bonds has both disulfide bonds and hydrogen bonds, and the disulfide bonds and hydrogen bonds have self-healing functions. The disulfide bond is self-healing through a dynamic exchange reaction, and the structural formula of the dynamic exchange reaction is as follows:

The present invention also provides a method for preparing a bifunctional self-healing polymer electrolyte, comprising the following steps:

S1: react the monomer with a double bond and the monomer with a disulfide bond in the first solution, and obtain a crosslinking agent with a disulfide bond through a nucleophilic addition reaction;

S2: Dissolve the cross-linking agent with disulfide bond obtained in S1 and the polyethylene glycol with double bond in the second solvent, add an initiator and a chain transfer reagent, and after deoxygenation, heating reaction to obtain PEG-SS copolymer;

S3: Dissolving the PEG-SS copolymer obtained in S2 in a third solvent, adding lithium salt and stirring evenly, casting the mixed solution to form a film, and drying to obtain a bifunctional self-healing polymer electrolyte.

Wherein, the first solvent is one or more of tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone, and the second solvent is tetrahydrofuran, dimethylsulfoxide, N,N - one or more of dimethylformamide, N-methylpyrrolidone, and the third solvent are tetrahydrofuran, dimethylsulfoxide, N,N-dimethylformamide, N-methylpyrrolidone One or more; the above-mentioned solvents are all aprotic solvents with good solubility and ability to combine with protons.

Specifically, in step S1, the monomer with double bond is 2-isocyanoethyl acrylate or isocyanoethyl methacrylate, and the molecular structural formula is respectively:

The above two isocyanates are different in their reactivity towards the reaction depending on whether or not they have methyl groups.

Further, the monomers with disulfide bonds are cystamine dihydrochloride, bis(2-hydroxyethyl) disulfide, 4,4'-diaminodiphenyldisulfide, 4,4'-dihydroxydisulfide Phenyl disulfide, the molecular structure is:

Among them, 2-isocyanoethyl acrylate or isocyanoethyl methacrylate are isocyanates, cystamine dihydrochloride and 4,4'-diaminodiphenyldisulfide are monomers containing amino groups, amino groups and isocyanates The urea group generated by the reaction has a hydrogen bond effect, and the reaction of the monomer with amino group and isocyanate does not require the use of a catalyst; in addition, bis(2-hydroxyethyl) disulfide and 4,4'-dihydroxydiphenyl disulfide are For monomers containing hydroxyl groups, the urethane groups formed by the reaction of hydroxyl groups and isocyanates have hydrogen bonds. The reaction of monomers with hydroxyl groups and isocyanates requires the use of a catalyst, and the catalyst is preferably dibutyltin dilaurate. The mechanical properties of monomers with disulfide bonds are affected by whether they have a benzene ring, and further affect the self-healing properties.

Further, the molar ratio of the monomer with a double bond and the monomer with a disulfide bond is 1:6 to 1:2; the monomer with a double bond and the monomer with a disulfide bond are in the first The temperature of the reaction in the solvent is 25°C to 80°C, and the reaction is carried out under stirring for 1 hour to 18 hours. Under the above molar ratio and reaction range, the reaction activity is the largest and the yield is the highest.

In addition, in step S1, the initiator is azobisisobutyronitrile; the chain transfer reagent is 2-cyano-2-propylbenzenedisulfide.

Further, in step S2, the polyethylene glycol with double bond is methoxy polyethylene glycol acrylate PEGA or polyethylene glycol methyl ether methacrylate PEGMA, and the structural formula is respectively:

Among them, n=7～45; the polyethylene glycol with double bond has different reactivity to the reaction because of whether it has a methyl group or not. The molecular weight of the polyethylene glycol with double bond in the present invention is 500-2000.

Further, the molar ratio of the polyethylene glycol with double bond and the crosslinking agent with disulfide bond is 100:(10～40); the reaction conditions of the two in the second solvent are: at 60～120℃ The reaction is stirred for 14 to 24 hours. Under the above molar ratio and reaction range, the reaction activity is the largest and the yield is the highest.

In addition, in step S2, the introduced protective gas is argon or nitrogen.

In step S3, the lithium salt is selected from one or more of lithium perchlorate, lithium bistrifluoromethylsulfonimide, lithium bisfluorosulfonimide, lithium tetrafluoroborate, and lithium hexafluorophosphate; the The molar ratio of the lithium salt to the ethylene oxide EO segment in the PEG-SS copolymer is 1:8 to 1:25. The addition of lithium salt will electrolyze lithium ions in the solution, and lithium ions will continuously combine and dissociate with the EO segment of ethylene oxide.

In the bifunctional self-healing polymer electrolyte of the present invention, a disulfide bond is introduced into the polymer to prepare a self-healing electrolyte material, and the introduction of the disulfide bond is a very effective method for improving the life and stability of the material. It provides the possibility for the self-healing properties of the material, firstly because the bond energy of the disulfide bond is low and it can undergo a reversible exchange dynamic equilibrium reaction under mild conditions, and secondly, the translocation of the disulfide can also be performed without external stimulation. occurs, which opens the possibility for self-healing of electrolyte materials at room temperature. Then it can be seen that the self-healing material with reversible covalent bonds is prepared through the introduction of disulfide bonds into the material through its reversible dynamic equilibrium. Better to extend the life of the material and improve the safety of the material.

The bifunctional self-healing polymer electrolyte of the present invention not only solves the battery damage caused by collision or bending of the lithium ion battery, but also enables the lithium ion battery to self-heal at room temperature without external stimulation. It focuses on the self-healing and repair of damaged lithium-ion batteries, using the dynamic exchange reaction of disulfide bonds, and translocation can also occur without external stimulation, providing the possibility for self-healing.

In the preparation method of the bifunctional self-healing polymer electrolyte of the present invention, the prepared cross-linking agent with disulfide bond is cross-linked with PEGA or PEGMA to obtain a PEG-SS copolymer. Compared with the existing technology, the self-healing effect of the copolymer PEG-SS is better, and the mechanical properties, self-healing effect and electrochemical performance of the polymer electrolyte are improved.

In the preparation method of the bifunctional self-healing polymer electrolyte of the present invention, in the preparation, PEGA or PEGMA with different molecular weights and different cross-linking agents with disulfide bonds, and then these prepolymers with different molecular weights are mixed with Cross-linking agents with different structures of disulfide bonds are cross-linked to form a polymer cross-linked network. On the one hand, prepolymers with different molecular weights have a great influence on the electrical conductivity and mechanical properties of polymer materials; on the other hand, different Among crosslinkers with disulfide bonds, cystamine dihydrochloride, bis(2-hydroxyethyl)disulfide, 4,4'-diaminodiphenyldisulfide or 4,4'-dihydroxydiphenyl The self-healing properties of disulfide to self-healing materials are also different, so the most suitable self-healing electrolyte material is studied, and the amount of the experimental drug in the reaction is matched to control the experiment.

Described below in conjunction with specific embodiments:

Example 1

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is Acrylic acid 2-isocyanoethyl ester and cystamine dihydrochloride are reacted to obtain, and the molar ratio of the two is 1:6; polyethylene glycol with double bond is polyethylene glycol methyl ether methacrylate, polyethylene glycol The molecular weight of methyl alcohol methyl ether methacrylate is 2000, and its molar ratio to the crosslinking agent with disulfide bond is 100:10. Lithium perchlorate is added to the above self-healing polymer, and the amount added is based on the self-healing polymer. The molar ratio of the ethoxylate segment and Li ion in the material is 25:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 5.5 g of 2-isocyanoethyl acrylate and 1.0 g of cystamine dihydrochloride were reacted in a tetrahydrofuran solvent, stirred at 25° C. for 16 hours, and the reaction product was filtered and vacuum-dried to obtain a disulfide band bond crosslinker monomer;

S2: Dissolve 0.5 g of the cross-linking agent with disulfide bonds obtained in step S1 and 21.6 g of polyethylene glycol methyl ether methacrylate with a molecular weight of 2000 in tetrahydrofuran, add initiator and chain transfer reagent, and deoxidize The post-protective gas is argon, heated to 60°C, reacted for 18 hours, and dried to obtain the PEG-SS copolymer;

S3: Dissolve the PEG-SS copolymer obtained in step S2 in dimethyl sulfoxide solvent, add lithium perchlorate, and set the molar ratio of ethoxy segment:Li in the polymer to 25:1. The film was cast in the mold, then dried at room temperature for 12 hours, and then dried at 60°C for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 50 microns, and a dual-functional self-healing polymer electrolyte was obtained.

Figure 1 shows the lithium ion conductivity of the polymer electrolyte obtained in Example 1. The conductivity varies with temperature from 23 to 100°C. According to the calculation formula of ionic conductivity σ=L/R×A, L is the self-healing polymer The thickness of the electrolyte, R is the measured resistance value, A is the area of the self-healing polymer electrolyte, and the lithium ion conductivity of the polymer electrolyte is calculated to be 7.51×10-5S/cm at 60°C.

Figure 2 shows the electrochemical stability window of the polymer electrolyte obtained in Example 1. The applied voltage is in the range of 0-6V. At a scan rate of 1mV/s, the most positive potential of the polymer electrolyte is about 5.1V, indicating that The polymer electrolyte of this example is very stable at high voltages.

Fig. 3 is a charge-discharge test of the polymer electrolyte prepared in Example 1. The present invention adopts the positive electrode material of LiFePO4, and prepares the positive electrode plate according to LiFePO4:carbon black:polyvinylidene fluoride=8:1:1, and in the glove box Assembled into a Li/polymer electrolyte membrane/LiFePO4 half-cell; the cut-off voltage range is 2.5V-4.2V, after standing for 10 hours, the charge-discharge performance was tested at a current density of 0.1C at 60°C. The results are as follows: The first cycle of discharge The specific capacity is 142.3 mAh/g, and the discharge specific capacity reaches 138.3 mAh/g after 100 cycles, indicating that the battery assembled with the polymer electrolyte provided in this example has a Coulombic efficiency of over 99%.

Figure 4 shows the self-healing performance test of the polymer electrolyte prepared in Example 1. The polymer electrolyte was cut into two sections and completely healed after 30 minutes at room temperature.

Example 2

In this embodiment, a bifunctional self-healing polymer electrolyte includes a cross-linking agent with disulfide bonds, polyethylene glycol, an initiator and a chain transfer agent, wherein the cross-linking agent with disulfide bonds is methacrylic acid isoform It is obtained by reacting cyanoethyl ester with 4,4'-diaminodiphenyl disulfide, the molar ratio of the two is 1:5; the polyethylene glycol with double bond is methoxy polyethylene glycol acrylate, methoxy The molecular weight of polyethylene glycol acrylate is 2000, and its molar ratio to the crosslinking agent with disulfide bond is 100:15; Lithium bis-trifluoromethanesulfonimide is added to the above-mentioned self-healing polymer, and the addition amount According to the molar ratio of the ethoxylate segment and Li ion in the self-healing polymer, it is 20:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 3.1 g of isocyanoethyl methacrylate was reacted with 1.0 g of 4,4'-diaminodiphenyldisulfide in N,N-dimethylformamide solvent, and stirred at 30°C for 14 hours , the reaction product is filtered and vacuum-dried to obtain the crosslinking agent monomer with disulfide bond;

S2: Dissolve 0.5 g of the crosslinking agent with disulfide bonds obtained in step S1 and 9.9 g of methoxy polyethylene glycol acrylate with a molecular weight of 2000 in N,N-dimethylformamide, and add an initiator , After deoxygenation of the chain transfer reagent, the protective gas is argon, heated to 70°C, reacted for 16 hours, and dried to obtain a PEG-SS copolymer;

S3: Dissolve the PEG-SS copolymer obtained in step S2 in tetrahydrofuran solvent, add lithium bis-trifluoromethanesulfonimide, and stir evenly according to the molar ratio of ethoxy segment in the polymer:Li 20:1 Then, the film was cast in a mold, then dried at room temperature for 12 hours, and then dried at 60 °C for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 100 microns, and a self-healing polymer electrolyte with dual functions was obtained. .

The lithium ion conductivity of the polymer electrolyte provided in this example is 7.13×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 5.03V; the first-cycle discharge specific capacity of the battery is 140.1mAh/g .

Example 3

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is Isocyanoethyl methacrylate and cystamine dihydrochloride are reacted to obtain, the molar ratio of the two is 1:4; polyethylene glycol with double bond is polyethylene glycol methyl ether methacrylate, polyethylene glycol The molecular weight of glycol methyl ether methacrylate is 1000, and its molar ratio to the crosslinking agent with disulfide bond is 100:20; Lithium bisfluorosulfonimide is added to the above self-healing polymer, and the addition amount is The molar ratio of the ethoxylate segment and Li ion in the self-healing polymer is 16:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 3.6 g of isocyanoethyl methacrylate and 1.0 g of cystamine dihydrochloride were reacted in a tetrahydrofuran solvent, stirred at 30° C. for 16 hours, and the reaction product was filtered and vacuum-dried to obtain a disulfide band bond crosslinker monomer;

S2: Dissolve 0.5 g of the cross-linking agent with disulfide bonds obtained in step S1 and 5.4 g of polyethylene glycol methyl ether methacrylate with a molecular weight of 1000 in N,N-dimethylformamide, add initiator The PEG-SS copolymer was obtained by heating to 80 °C under the protective gas of argon after deoxygenation of the reagent and the chain transfer reagent, reacting for 18 hours, and drying;

S3: Dissolve the PEG-SS copolymer obtained in step S2 in dimethyl sulfoxide solvent, add lithium bisfluorosulfonimide, and stir evenly according to the molar ratio of ethoxy segment:Li in the polymer to 16:1 Then, it was cast in a mold to form a film, then dried at room temperature for 12 hours, and then dried at 60 °C for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 200 microns, and a self-healing polymer electrolyte with dual functions was obtained. .

The lithium ion conductivity of the polymer electrolyte provided in this example is 5.74×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.93V; the first-cycle discharge specific capacity of the battery is 138.5mAh/g .

Example 4

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is Acrylic acid 2-isocyanoethyl ester and 4,4'-diaminodiphenyl disulfide react to obtain, the molar ratio of the two is 1:3; the polyethylene glycol with double bond is methoxy polyethylene glycol acrylic acid ester, the molecular weight of methoxy polyethylene glycol acrylate is 1000, and its molar ratio to the crosslinking agent with disulfide bond is 100:25; lithium tetrafluoroborate is added to the above-mentioned self-healing polymer, and the amount added is 100:25. The molar ratio of ethoxylate segment and Li ion in the self-healing polymer is 12:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 1.9 g of 2-isocyanoethyl acrylate was reacted with 1.0 g of 4,4'-diaminodiphenyl disulfide in N-methylpyrrolidone solvent, stirred at 45°C for 14 hours, and the reaction product was extracted After filtration and vacuum drying, the crosslinking agent monomer with disulfide bond is obtained;

S2: Dissolve 0.5 g of the crosslinking agent with disulfide bonds obtained in step S1 and 3.6 g of methoxy polyethylene glycol acrylate with a molecular weight of 1000 in N,N-dimethylformamide, and add an initiator , After deoxygenation of the chain transfer reagent, the protective gas is argon, heated to 90°C, reacted for 20 hours, and dried to obtain PEG-SS copolymer;

S3: Dissolve the PEG-SS copolymer obtained in step S2 in tetrahydrofuran solvent, add lithium tetrafluoroborate, set the molar ratio of ethoxy segment:Li in the polymer to 12:1, stir evenly, and cast in a mold A film was formed, then dried at room temperature for 12 hours, and then dried at 60° C. for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 100 microns, and a self-healing polymer electrolyte with dual functions was obtained.

The lithium ion conductivity of the polymer electrolyte provided in this example is 3.64×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.7V; the first-cycle discharge specific capacity of the battery is 133.1mAh/g .

Example 5

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is Acrylic acid 2-isocyanoethyl ester and bis(2-hydroxyethyl) disulfide react to obtain, the molar ratio of the two is 1:4; polyethylene glycol with double bond is methoxy polyethylene glycol acrylate , the molecular weight of methoxy polyethylene glycol acrylate is 500, and its molar ratio to the crosslinking agent with disulfide bond is 100:30; lithium hexafluorophosphate is added to the above self-healing polymer, and the amount of addition is based on the self-healing polymer. The molar ratio of the ethoxy segment and Li ion in the material is 20:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 3.7 g of 2-isocyanoethyl acrylate, 1.0 g of bis(2-hydroxyethyl) disulfide and 0.01 g of dibutyltin dilaurate catalyst were reacted in tetrahydrofuran solvent, stirring at 60°C After 4 hours, the reaction product was filtered and vacuum-dried to obtain a crosslinking agent monomer with a disulfide bond;

S2: Dissolve 0.5 g of the cross-linking agent with disulfide bonds obtained in step S1 and 2.1 g of methoxy polyethylene glycol acrylate with a molecular weight of 500 in dimethyl sulfoxide, add an initiator and a chain transfer reagent, and pass After deoxygenation, the protective gas is nitrogen, heated to 90°C, reacted for 20 hours, and dried to obtain a PEG-SS copolymer;

S3: Dissolve the PEG-SS copolymer obtained in step S2 in N-methylpyrrolidone solvent, add lithium hexafluorophosphate, according to the molar ratio of ethoxy segment:Li in the polymer is 12:1, after stirring evenly, in the mold Cast into a film, then dry at room temperature for 12 hours, and then dry at 60°C for 24 hours. The thickness of the polymer electrolyte membrane produced in this embodiment is 150 microns, and a dual-functional self-healing polymer electrolyte is obtained.

The lithium ion conductivity of the polymer electrolyte provided in this example is 2.89×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.61V; the first-cycle discharge specific capacity of the battery is 139.1mAh/g .

Example 6

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is It is obtained by reacting isocyanoethyl methacrylate with 4,4'-dihydroxydiphenyl disulfide, the molar ratio of the two is 1:4, and the polyethylene glycol with double bond is polyethylene glycol methyl ether methyl Acrylate, the molecular weight of polyethylene glycol methyl ether methacrylate is 1000, and its molar ratio to the crosslinking agent with disulfide bond is 100:35; lithium perchlorate is added to the above self-healing polymer, adding The amount is 16:1 according to the molar ratio of ethoxylate segment and Li ion in the self-healing polymer; the present embodiment provides a bifunctional self-healing polymer electrolyte and its preparation method is as follows;

S1: react 2.5g of isocyanoethyl methacrylate with 1.0g of 4,4'-dihydroxydiphenyl disulfide and 0.01g of dibutyltin dilaurate catalyst in tetrahydrofuran solvent, at 70°C, After stirring for 3 hours, the reaction product was filtered and vacuum-dried to obtain the crosslinking agent monomer with disulfide bond;

S2: Dissolve 0.5 g of the cross-linking agent with disulfide bonds obtained in step S1 and 2.6 g of methoxy polyethylene glycol acrylate with a molecular weight of 1000 in dimethyl sulfoxide, add an initiator and a chain transfer reagent, and pass After deoxygenation, the protective gas was nitrogen, heated to 100°C, reacted for 22 hours, and dried to obtain a PEG-SS copolymer;

S3: Dissolving the PEG-SS copolymer obtained in step S2 in N-methylpyrrolidone solvent, adding lithium perchlorate, according to the molar ratio of ethoxy segment in the polymer:Li 16:1, after stirring evenly, The film was cast in a mold, then dried at room temperature for 12 hours, and then dried at 60°C for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 250 microns, and a dual-functional self-healing polymer electrolyte was obtained.

The lithium ion conductivity of the polymer electrolyte provided in this example is 5.32×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.52V; the first-cycle discharge specific capacity of the battery is 131.7mAh/g .

Example 7

In this embodiment, a bifunctional self-healing polymer electrolyte includes a crosslinking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the crosslinking agent with disulfide bonds is It is obtained by reacting isocyanoethyl methacrylate with bis(2-hydroxyethyl) disulfide, and the molar ratio of the two is 1/2.5; the polyethylene glycol with double bond is methoxy polyethylene glycol acrylate , the molecular weight of methoxy polyethylene glycol acrylate is 500, and its molar ratio to the crosslinking agent with disulfide bonds is 100:40; lithium perchlorate is added to the above-mentioned self-healing polymer, and the addition amount is based on the self-healing polymer. The molar ratio of the ethoxylate segment and Li ion in the healing polymer is 12:1; the preparation method of the bifunctional self-healing polymer electrolyte in this embodiment is as follows;

S1: 2.5 g of isocyanoethyl methacrylate was reacted with 1.0 g of bis(2-hydroxyethyl) disulfide and 0.01 g of dibutyltin dilaurate catalyst in dimethyl sulfoxide solvent at 80°C stirring for 2 hours, the reaction product was filtered and vacuum-dried to obtain the crosslinking agent monomer with disulfide bond;

S2: Dissolve 0.5 g of the crosslinking agent with disulfide bonds obtained in step S1 and 1.4 g of methoxy polyethylene glycol acrylate with a molecular weight of 500 in dimethyl sulfoxide, add an initiator and a chain transfer reagent, and pass After deoxygenation, the protective gas was nitrogen, heated to 110°C, reacted for 23 hours, and dried to obtain a PEG-SS copolymer;

S3: Dissolving the PEG-SS copolymer obtained in step S2 in N-methylpyrrolidone solvent, adding lithium perchlorate, according to the molar ratio of ethoxy segment:Li in the polymer is 12:1, after stirring evenly, The film was cast in a mold, then dried at room temperature for 12 hours, and then dried at 60°C for 24 hours. The thickness of the polymer electrolyte membrane produced in this implementation was 250 microns, and a dual-functional self-healing polymer electrolyte was obtained.

The lithium ion conductivity of the polymer electrolyte provided in this example is 1.94×10-5S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.21V; the first-cycle discharge specific capacity of the battery is 129.7mAh/g .

Example 8

A self-healing polymer electrolyte with dual functions, comprising a cross-linking agent with disulfide bonds, polyethylene glycol with double bonds, an initiator and a chain transfer agent, wherein the cross-linking agent with disulfide bonds is acrylic acid Obtained by reacting 2-isocyanoethyl ester with 4,4'-dihydroxydiphenyl disulfide, the molar ratio of the two is 1:2; the polyethylene glycol with double bond is polyethylene glycol methyl ether methacrylic acid ester, the molecular weight of polyethylene glycol methyl ether methacrylate is 1000, and its molar ratio to the crosslinking agent with disulfide bonds is 100:35; adding lithium bisfluorosulfonimide to the above self-healing polymer , the addition amount is 8:1 according to the molar ratio of the ethoxylate segment in the self-healing polymer to Li ions; the preparation method of the bifunctional self-healing polymer electrolyte of the present embodiment is as follows;

S1: 1.2g of 2-isocyanoethyl acrylate, 1.0g of 4,4'-dihydroxydiphenyl disulfide and 0.01g of dibutyltin dilaurate catalyst in N,N-dimethylformamide Reaction in a solvent, stirring at 80°C for 1 hour, the reaction product is suction filtered and vacuum dried to obtain a crosslinking agent monomer with a disulfide bond;

S2: Dissolve 0.5 g of the cross-linking agent with disulfide bonds obtained in step S1 and 2.6 g of polyethylene glycol methyl ether methacrylate with a molecular weight of 1000 in dimethyl sulfoxide, add initiator and chain transfer reagent After deoxygenation, the protective gas is nitrogen, heated to 120°C, reacted for 24 hours, and dried to obtain PEG-SS copolymer;

S3: Dissolve the PEG-SS copolymer obtained in the step S2 in N-methylpyrrolidone solvent, add lithium bisfluorosulfonimide, and the molar ratio of ethoxy segment in the polymer:Li is 8:1 , after stirring evenly, cast the film in the mold, then dry at room temperature for 12 hours, and then dry at 60 ° C for 24 hours. polymer electrolyte.

The lithium ion conductivity of the polymer electrolyte provided in this example is 9.66×10-6S/cm at 60°C; the most positive potential of the electrochemical stability window is 4.45V; the first-cycle discharge specific capacity of the battery is 135.8mAh/g .

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (10)

1. The bifunctional self-healing polymer electrolyte is characterized by comprising polyethylene glycol with double bonds, a cross-linking agent with disulfide bonds, an initiator and a chain transfer agent; wherein the cross-linking agent with the disulfide bond simultaneously has the disulfide bond and the hydrogen bond, and the disulfide bond and the hydrogen bond have a self-healing function.

2. A bifunctional self-healing polymer electrolyte according to claim 1, wherein the disulfide bonds are self-healing via a dynamic exchange reaction having the following structural formula:

3. a method for preparing a bifunctional self-healing polymer electrolyte according to claim 1 or 2, comprising the steps of:

s1: reacting a monomer with double bonds with a monomer with disulfide bonds in a first solution, and obtaining a cross-linking agent with disulfide bonds through a nucleophilic addition reaction;

s2: dissolving the cross-linking agent with the disulfide bond and the polyethylene glycol with the double bond obtained in the step S1 in a second solvent, adding an initiator and a chain transfer reagent, removing oxygen, and heating to react to obtain a PEG-SS copolymer;

s3: and (3) dissolving the PEG-SS copolymer obtained in the S2 in a third solvent, adding lithium salt, uniformly stirring, pouring the obtained mixed solution into a film, and drying to obtain the bifunctional self-healing polymer electrolyte.

4. The method according to claim 3, wherein in step S1, the double-bonded monomer is 2-isocyanoethyl acrylate or isocyanoethyl methacrylate, and the molecular structural formulas are respectively:

5. the method according to claim 3, wherein in step S1, the monomer with disulfide bond is one or more of cystamine dihydrochloride, bis (2-hydroxyethyl) disulfide, 4 '-diaminodiphenyl disulfide, and 4,4' -dihydroxydiphenyl disulfide, and the molecular structural formulas are as follows:

6. the method according to claim 3, wherein in step S1, the molar ratio of the double-bond monomer to the disulfide-bond monomer is 1:6 to 1: 2.

7. The method according to claim 3, wherein in step S2, the double-bonded polyethylene glycol is methoxypolyethylene glycol acrylate PEGA or polyethylene glycol methyl ether methacrylate PEGMA, and the structural formulas are respectively:

wherein n is 7-45.

8. The method according to claim 3, wherein in step S2, the molar ratio of the double-bonded polyethylene glycol to the cross-linking agent with disulfide bonds is 100 (10-40).

9. A method according to claim 3, wherein in step S3, the lithium salt is selected from one or more of lithium perchlorate, lithium bis (trifluoromethyl) sulfonyl imide, lithium bis (fluoro) sulfonyl imide, lithium tetrafluoroborate and lithium hexafluorophosphate.

10. The method for preparing a bifunctional self-healing polymer electrolyte according to any one of claims 3 to 8, wherein the first solvent, the second solvent, and the third solvent are one or more of tetrahydrofuran, dimethylsulfoxide, N-dimethylformamide, and N-methylpyrrolidone.

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