A self-healing adhesive, its preparation method and use

Abstract

The present application relates to the technical field of battery binder, especially to a self-healing adhesive and its preparation method and application, the self-healing adhesive of the present application takes polyamino acid as the main chain structure of the adhesive, and introduces disulfide bond in the adhesive, wherein, amino acid can form strong interaction force with active substances due to a large number of amino and carboxyl and other polar functional groups, thereby solving the phenomenon of pole piece powder falling in non-aqueous aluminum ion battery.The introduction of disulfide bond gives the adhesive certain self-healing performance, when the active material in the pole piece is affected by external force or environmental factors to produce cracks, the disulfide bond breaks, the generated sulfur atom reacts with oxygen in the air to form sulfur dioxide and other compounds, when these compounds meet sulfur free radicals, chemical reaction occurs, and the disulfide bond is reformed, the process does not need external energy input, so it can realize the self-healing of active material, and further reduce the expansion of cracks.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery binder, in particular to a self-healing adhesive and a preparation method and application thereof. BACKGROUND

[0002] At present, due to the problems of high cost and safety hazards of lithium ion batteries, people are trying to find another new energy storage system to replace lithium ion batteries. Among them, aluminum ion batteries have entered the field of vision because of their rich crust content, low price and high safety. Aluminum ion batteries are divided into aqueous aluminum ion batteries and non-aqueous aluminum ion batteries, which are composed of four parts of positive and negative electrodes, separators and electrolytes. As a less active substance in the positive and negative electrodes, the binder still plays a crucial role.

[0003] In the prior art, the commonly used binders in non-aqueous aluminum ion batteries mainly include three categories of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR) and polytetrafluoroethylene (PTFE), but there is a common problem that in the cycle process, due to the relatively weak adhesion, cracks are easily expanded, active substances are easily detached, and then the battery is disabled.

[0004] For example, Chinese invention patent CN106486661A discloses a composite positive electrode based on metal oxide and carbon nanotube, a preparation method and an aluminum ion battery, and specifically discloses that the binder includes polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride, polystyrene butadiene copolymer, fluorinated rubber and polyurethane, polyvinyl pyrrolidone, polyethyl acrylate, polyvinyl chloride, polyacrylonitrile, polycaprolactam, polybutadiene, polyisoprene, polyacrylic acid, and derivatives, mixtures or copolymers thereof. The above-mentioned binders cannot timely and effectively repair the cracks generated by the active substances, and there is a risk of battery failure caused by the detachment of active substances.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a self-healing adhesive and a preparation method thereof. The self-healing adhesive not only can form a strong interaction with the active substances in the battery pole piece, but also can timely repair the cracks generated by the active substances, thereby effectively reducing the expansion of the cracks.

[0007] In a first aspect, the present application provides a self-healing adhesive, and the structural formula of the self-healing adhesive is:

[0008]

[0009] wherein R1 includes any one of a methyl group, an ethyl group, a propyl group, and a butyl group, and is preferably a methyl group which has a small steric hindrance, R2 and R3 include any one of a hydrogen atom, a hydroxyl group, an amino group, an alkoxy group, an alkyl group, an alkoxyalkyl group, and an aryl group-substituted secondary amine group, and R2 and R3 are preferably the same substituent. 10 wherein R1 includes any one of a methyl group, an ethyl group, a propyl group, and a butyl group, and is preferably a methyl group which has a small steric hindrance, R2 and R3 include any one of a hydrogen atom, a hydroxyl group, an amino group, an alkoxy group, an alkyl group, an alkoxyalkyl group, and an aryl group-substituted secondary amine group, and R2 and R3 are preferably the same substituent.

[0010] The self-healing adhesive of the present application has a main chain structure of polyamino acid, and a disulfide bond is introduced into the adhesive, wherein the amino acid can form a strong interaction force with active substances due to a large number of polar functional groups such as amino groups and carboxyl groups, thereby solving the phenomenon of powder falling of the pole piece in the non-aqueous aluminum ion battery. The introduction of the disulfide bond gives the adhesive certain self-healing performance, which can timely repair the material and thereby reduce the crack propagation.

[0011] The self-healing adhesive of the present application is mainly prepared by directly or indirectly introducing a disulfide bond into polyamino acid. The introduction of the disulfide bond is mainly achieved by reacting a hydroxyl group in a thiol-hydroxyl compound with a carboxyl group in polyamino acid to introduce a thiol group, and further forming a disulfide bond through the redox action of the thiol group, or directly introducing a disulfide bond by reacting an amino group in a disulfide-amino compound with a carboxyl group in polyamino acid.

[0012] In a second aspect, the present application specifically discloses a method for preparing the self-healing adhesive by indirectly introducing a disulfide bond, comprising the following steps:

[0013] S1, dissolving polyglutamic acid in an organic solvent, and sequentially adding a dehydrogenation reagent and a halogen-substituted alkyl group, and then treating the reacted solution by centrifugation and rotary evaporation to obtain an intermediate A;

[0014] S2, dissolving the intermediate A in an organic solvent, and adding the intermediate A dropwise into a thiol-hydroxyl compound under the action of an acidic catalyst, and then treating the reacted substance by filtration and washing to obtain an intermediate B;

[0015] S3, adding an excess of an oxidizing agent dropwise into the intermediate B, and then adding a reducing agent to react with the excess of the oxidizing agent after the reaction is completed, and then drying the reacted product to obtain the self-healing adhesive.

[0016] The reaction mechanism of the synthesis method is as follows:

[0017]

[0018]

[0019] In step S1, first, polyglutamic acid is dissolved in an organic solvent, a hydrogen-abstracting agent is added, and the reaction is carried out for 1 to 3 hours. Then, a halogen-substituted alkyl group is added to the solution after the reaction, and the reaction is carried out for 2 to 4 hours, so that -H in the terminal -NH2 in the polyglutamic acid is changed to an alkyl group, to avoid self-crosslinking of the amino acid during the reaction. The solution obtained by the reaction is centrifuged, the supernatant is taken, and rotary evaporation is performed to remove the organic solvent, to obtain an intermediate A.

[0020] The hydrogen-abstracting agent includes any one of potassium carbonate, sodium hydride, potassium hydride, n-butyllithium, and potassium tert-butoxide, and is preferably potassium carbonate.

[0021] The halogen-substituted alkyl group includes any one of methyl iodide, methyl chloride, ethyl iodide, 1-iodopropane, and butyl iodide, and is preferably methyl iodide and methyl chloride.

[0022] The organic solvent includes a polar solvent having a low boiling point, such as methanol, dichloromethane, and trichloromethane.

[0023] The amount of the halogen-substituted alkyl group is 2 to 3 times, and preferably 2 times, the molar amount of the amino group in the polyglutamic acid.

[0024] During the rotary evaporation, the temperature is controlled to be 40 to 50°C, to remove the organic solvent from the reaction product.

[0025] In step S2, first, the intermediate A is dissolved in an organic solvent, and an acidic solution is used as a catalyst. The dissolved intermediate A is added dropwise to a thiol-hydroxyl compound, and after the reaction is sufficiently completed, the obtained substance is filtered, and washed with brine, to obtain an intermediate B.

[0026] The organic solvent includes a polar solvent having a low boiling point, such as methanol, dichloromethane, and trichloromethane.

[0027] The acidic catalyst includes any one of concentrated sulfuric acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid, and is preferably concentrated sulfuric acid. The amount of the acidic catalyst is 0.5 to 2% of the total amount of the reaction system.

[0028] The thiol-hydroxyl compound is a substance containing both a hydroxyl group and a mercapto group, such as any one of 2-mercaptoethanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, and hydroxyl-polyethylene glycol-mercapto. The amount of the thiol-hydroxyl compound is 8 to 12 times, and preferably 10 times, the molar amount of the hydroxyl group in the intermediate A, based on the molar amount of the hydroxyl group in the molecule.

[0029] As the preferred technical solution, in step S2, the reaction is controlled at a temperature of 60-80°C for 6-10 hours.

[0030] In step S3, the diluted oxidizing agent is added dropwise to the intermediate B, and a disulfide bond is formed by the redox reaction of the thiol group. After the reaction, a reducing agent is added to react with the excess oxidizing agent. The reaction product is dried in a vacuum oven at 70-90°C for 10-20 hours to obtain the self-healing adhesive.

[0031] The oxidizing agent includes any one of iodine solution, dimethyl sulfoxide, and hydrogen peroxide, i.e., a mild oxidation reaction such as air oxidation or DMSO oxidation is used, and the reaction is performed under near neutral or weak alkaline conditions (pH value of 6.5-10) for more than 24 hours; or a severe reaction condition such as H2O2 can be used; for iodine solution, 10-15 mol / L iodine can be added for oxidation, and the reaction is performed for 15-40 minutes.

[0032] When the oxidizing agent is iodine solution, the molar ratio of intermediate B to iodine solution is 1:1, and the iodine solution corresponds to two electrons, while the thiol group loses two electrons to form the final disulfide bond.

[0033] The reducing agent includes any one of ascorbic acid, sodium sulfite, and sodium bisulfite, and is mainly used to react with the excess oxidizing agent.

[0034] In a third aspect, the application specifically discloses a method for preparing a self-healing adhesive by directly introducing a disulfide bond, comprising the following steps:

[0035] T1, dissolving polyglutamic acid in an organic solvent, and sequentially adding a hydrogen abstraction reagent and a halogen-substituted alkyl group, and after the reaction, the solution is treated by centrifugation and rotary evaporation to obtain intermediate A;

[0036] T2, dissolving intermediate A and a disulfide bond-amino compound in an organic solvent, and after the reaction, the product is treated by rotary evaporation and drying to obtain the self-healing adhesive.

[0037] The reaction mechanism of the synthesis method is as follows:

[0038]

[0039] In step T2, the disulfide bond-amino compound refers to a substance containing a disulfide bond and capable of reacting with the carboxyl group in polyglutamic acid, and specifically includes any one of 4,4'-dithiodianiline and bis(2-aminophenyl)disulfide.

[0040] The amount of the disulfide bond-amino compound is 1-2 times, and preferably 1.5 times, the molar amount of the amino group in the disulfide bond-amino compound, based on the molar amount of the amino group in the molecule.

[0041] In a fourth aspect, the application also provides the use of the self-healing adhesive in a non-aqueous aluminum ion battery, which also falls within the protection scope of the application.

[0042] Studies have shown that the self-healing adhesive of the application applied in the non-aqueous aluminum ion battery, the amino acids in the adhesive can form a strong interaction with the active material in the battery pole piece due to the presence of a large number of amino and carboxyl groups and other polar functional groups, thereby avoiding the shedding of the active material, and the presence of disulfide bonds can timely repair the material, realize the self-healing of the material, and thereby reduce the crack propagation and shedding of the active material, and prolong the service life of the battery.

[0043] The self-healing adhesive of the application has at least the following beneficial effects:

[0044] 1. The self-healing adhesive of the application takes polyamino acid as the main chain structure of the adhesive, and introduces disulfide bonds into the adhesive, wherein the amino acids can form a strong interaction force with the active material due to the presence of a large number of amino and carboxyl groups and other polar functional groups, thereby solving the phenomenon of pole piece powder falling in the non-aqueous aluminum ion battery. The introduction of disulfide bonds endows the adhesive with certain self-healing performance, when the active material in the pole piece is subjected to external force or environmental factors to produce cracks, the disulfide bonds are broken, the generated sulfur atoms react with oxygen in the air to form compounds such as sulfur dioxide, and these compounds diffuse in the material and chemically react with sulfur free radicals to re-form disulfide bonds. This process does not require external energy input, so it can timely repair the material and realize the self-healing of the material, thereby reducing the crack propagation;

[0045] 2. The self-healing adhesive of the application applied in the non-aqueous aluminum ion system has a significant improvement in the specific discharge capacity compared to the commonly used adhesive, and due to the formation of a three-dimensional network structure and the introduction of disulfide bonds, the self-healing performance of the adhesive is significantly improved, and the cycle performance is also significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0047] Figure 1 The influence of the self-healing adhesive of the application and the traditional sodium carboxymethyl cellulose adhesive on the cycle performance of the battery;

[0048] Figure 2SEM images of the self-healing adhesive of the present application before and after cycling;

[0049] Figure 3 SEM images of the conventional sodium carboxymethyl cellulose adhesive before and after cycling;

[0050] Figure 4 Cyclic voltammogram of a battery assembled using the self-healing adhesive of the present application;

[0051] Figure 5 State of the electrode sheet after drying of the coating of the self-healing adhesive of the present application;

[0052] Figure 6 State of the electrode sheet after drying of the coating of the adhesive of Comparative Example 1;

[0053] Figure 7 State of the electrode sheet after drying of the coating of the adhesive of Comparative Example 2;

[0054] Figure 8 State of the electrode sheet after drying of the coating of the adhesive of Comparative Example 3;

[0055] Figure 9 LSV curve for an electrode coated directly on the current collector with the self-healing adhesive of the present application, the electrode being an aluminum sheet. DETAILED DESCRIPTION

[0056] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0057] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0058] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0059] Example 1

[0060] S1, 1g polyglutamic acid (PGA) is dissolved in methanol, 0.3mg potassium carbonate (K2CO3) is added, and the reaction is carried out for 2h to play the role of hydrogen abstraction, and then 0.5mg iodomethane (CH3I) is added to the solution after the reaction, and the reaction is carried out for 3h to change the -H in the end group -NH2 in the PGA to -CH3, avoiding the self-crosslinking of the amino acid during the reaction;

[0061] The solution after the reaction is centrifuged, the supernatant is taken and rotary evaporation is carried out to obtain intermediate A;

[0062] S2, intermediate A is dissolved in toluene with concentrated sulfuric acid as a catalyst, and is added dropwise to 9g 6-mercaptohexan-1-ol, and the reaction is carried out at 70°C for 8h to make the reaction sufficient, the reaction product is filtered, and salt water is used for washing to obtain intermediate B;

[0063] S3, intermediate B is added dropwise to diluted iodine solution, and a disulfide bond is formed by the redox effect of the thiol group, ascorbic acid is added after the reaction to react with the excess iodine solution, and the reaction product is dried in a vacuum oven at 80°C for 12h to obtain a self-healing adhesive.

[0064] Example 2

[0065] S1, 1g polyglutamic acid (PGA) is dissolved in methanol, 0.05mg sodium hydride is added, and the reaction is carried out for 2h to play the role of hydrogen abstraction, and then 0.18mg chloromethane is added to the solution after the reaction, and the reaction is carried out for 3h to change the -H in the end group -NH2 in the PGA to -CH3, avoiding the self-crosslinking of the amino acid during the reaction;

[0066] The solution after the reaction is centrifuged, the supernatant is taken and rotary evaporation is carried out to obtain intermediate A;

[0067] S2, intermediate A is dissolved in toluene with concentrated sulfuric acid as a catalyst, and is added dropwise to 7.2g 3-mercapto-2-butanol, and the reaction is carried out at 70°C for 8h to make the reaction sufficient, the reaction product is filtered, and salt water is used for washing to obtain intermediate B;

[0068] S3, intermediate B is added dropwise to dimethyl sulfoxide, and a disulfide bond is formed by the redox effect of the thiol group, ascorbic acid is added after the reaction to react with the excess dimethyl sulfoxide, and the reaction product is dried in a vacuum oven at 80°C for 12h to obtain a self-healing adhesive.

[0069] Example 3

[0070] S1, 1g polyglutamic acid (PGA) is dissolved in methanol, 0.08mg potassium hydride is added, and the reaction is carried out for 2h to play the role of hydrogen abstraction, and then 0.5mg methyl iodide (CH3I) is added to the solution after the reaction, and the reaction is carried out for 3h to change the -H in the end group -NH2 in PGA to -CH3, avoiding the self-crosslinking of amino acids during the reaction;

[0071] The solution after the reaction is centrifuged, and the supernatant is taken for rotary evaporation to obtain intermediate A;

[0072] S2, intermediate A is dissolved in toluene with concentrated sulfuric acid as catalyst, and is added dropwise to 13.8g 11-mercapto-1-undecanol, and is reacted at 70℃ for 10h to make the reaction sufficient, the reaction product is filtered and washed with brine to obtain intermediate B;

[0073] S3, intermediate B is added dropwise to diluted iodine solution, and a disulfide bond is formed by the redox effect of thiol group, and ascorbic acid is added after the reaction to react the excess iodine solution, and the reaction product is dried in a vacuum oven at 80℃ for 12h to obtain a self-healing adhesive.

[0074] Example 4

[0075] T1, 1g polyglutamic acid (PGA) is dissolved in methanol, 0.3mg potassium carbonate (K2CO3) is added, and the reaction is carried out for 2h to play the role of hydrogen abstraction, and then 0.5mg methyl iodide (CH3I) is added to the solution after the reaction, and the reaction is carried out for 3h to change the -H in the end group -NH2 in PGA to -CH3, avoiding the self-crosslinking of amino acids during the reaction;

[0076] The solution after the reaction is centrifuged, and the supernatant is taken for rotary evaporation to obtain intermediate A;

[0077] T2, intermediate A and 2.5g 4,4'-dithiodianiline are dissolved in methanol solution, stirred at room temperature for 10h, the product after the reaction is rotary evaporated to remove methanol, and then dried in a vacuum oven at 80℃ for 12h to obtain a self-healing adhesive.

[0078] Example 5

[0079] T1, 1g polyglutamic acid (PGA) is dissolved in methanol, 0.13mg n-butyllithium is added, and the reaction is carried out for 2h to play the role of hydrogen abstraction, and then 0.5mg methyl iodide (CH3I) is added to the solution after the reaction, and the reaction is carried out for 3h to change the -H in the end group -NH2 in PGA to -CH3, avoiding the self-crosslinking of amino acids during the reaction;

[0080] The solution after the reaction is centrifuged, and the supernatant is taken for rotary evaporation to obtain intermediate A;

[0081] T2, intermediate A was dissolved in methanol solution with 16.8g bis(2- aminophenyl)disulfide, stirred at room temperature for 12h, the product of the reaction was removed by rotary evaporation to remove methanol, and then dried in a vacuum oven at 80°C for 12h to obtain a self-healing adhesive.

[0082] Example 6

[0083] T1, 1g polyglutamic acid (PGA) was dissolved in methanol, 0.05mg sodium hydride was added, and reacted for 2h to play a role of hydrogen abstraction, and then 0.5mg iodomethane was added to the solution after the reaction, and reacted for 3h to change the -H in the terminal -NH2 of PGA to -CH3, avoiding the self-crosslinking of amino acids during the reaction;

[0084] The solution after the reaction was centrifuged, and the supernatant was removed by rotary evaporation to obtain intermediate A;

[0085] T2, intermediate A was dissolved in methanol solution with 2.5g 4,4'- dithiodianiline, stirred at room temperature for 10h, the product of the reaction was removed by rotary evaporation to remove methanol, and then dried in a vacuum oven at 80°C for 12h to obtain a self-healing adhesive.

[0086] Comparative Example 1

[0087] 0.1g carboxymethyl cellulose sodium (CMC) was dissolved in 9.9ml water, stirred for 10h to obtain a traditional carboxymethyl cellulose sodium adhesive.

[0088] Comparative Example 2

[0089] 5mg PVDF was dissolved in 0.1mL NMP, stirred for 10h to obtain a PVDF solution with a volume fraction of 50mg / ml -1 .

[0090] Comparative Example 3

[0091] 7.69g dopamine was placed in a three-necked flask, 8.4g dihydropyran was added, and reacted for 3h under the condition of hydrochloric acid, the reactant was pretreated, and then 4.45g 3,3-dithiodipropionic acid was added and reacted at 40°C for 8h to obtain the product, which was then filtered and washed, and dried in an 80°C oven for 12h.

[0092] 0.1g product was dissolved in 9.9ml water, stirred for 10h to obtain a modified dopamine adhesive.

[0093] Test Example

[0094] The adhesives prepared in the above examples and comparative examples were applied to the assembly of batteries according to the following method, and the batteries were tested for electrochemical performance.

[0095] 1. Preparation and drying of slurry

[0096] According to the proportion of active material, conductive agent and binder solution mass ratio of 6:3:1, add graphite, kohlen black, binder solution in turn.

[0097] The specific operation steps are as follows: first, the active material (graphite) and the conductive agent (kohlen black) are pre-ground for a certain time, then the binder solution is added, and the grinding is continued until no particle feeling is felt, and the positive electrode slurry is prepared.

[0098] 2. Assembly of battery

[0099] Positive electrode tab preparation: first, a molybdenum sheet with a diameter of 8 mm is punched as a positive electrode current collector. It is ultrasonically cleaned with anhydrous ethanol and dried, and further weighed and recorded (m0); then, the positive electrode slurry is uniformly coated on the molybdenum sheet, placed in a vacuum oven and dried at 80℃ for 12h, weighed and recorded again (recorded as m), and the mass of active material (Δm) is obtained by subtracting the initial molybdenum sheet mass.

[0100] Negative electrode tab preparation: use a punch press to punch an aluminum sheet (Al) with a purity of 99.999% into a round sheet with a diameter of 8mm, and store it in a glove box for use.

[0101] Aluminum-based battery assembly: the assembly of rechargeable aluminum batteries uses a Swagelok mold, and the assembly sequence of the battery is positive shell, molybdenum sheet, separator, electrolyte, aluminum sheet and negative shell, and the electrochemical performance test is carried out after the open circuit voltage (OCV) is stable. Table 1 is the test results of the discharge specific capacity mAh / g of the battery after the battery is cycled for 30 times after the self-healing adhesive prepared in examples 1-6 and control examples 1-3 is applied to the battery assembly.

[0102] Table 1 test results

[0103]

[0104]

[0105] Figure 1 The influence of the self-healing adhesive of the application and the traditional sodium carboxymethyl cellulose adhesive on the cycle performance of the battery can be seen from the figure. The discharge specific capacity mAh / g of the battery after the self-healing adhesive of the application is applied to the battery assembly is still much higher than that of the traditional sodium carboxymethyl cellulose adhesive after the battery is cycled for 30 times.

[0106] Figure 2 The SEM images of the self-healing adhesive of the application before and after cycling can be found that the cracks are obviously reduced, indicating that the self-healing adhesive of the application has good adhesive performance and excellent self-healing performance;

[0107] Figure 3 For the SEM images of traditional sodium carboxymethyl cellulose binder before and after recycling, it can be found that the cracks obviously increase, indicating that the traditional sodium carboxymethyl cellulose binder does not have self-healing performance.

[0108] Figure 4 For the CV data, there is obvious redox peak, indicating that the pole piece made of the binder can normally work when assembled into a battery.

[0109] Figure 5 The state of the pole piece after the self-healing binder is coated and dried, and the surface has no obvious cracks, indicating that the self-healing binder can timely repair the material, realize self-healing of the material, and further reduce the expansion of cracks.

[0110] Figures 6-8 The state of the pole piece after the traditional sodium carboxymethyl cellulose binder, the PVDF binder and the modified dopamine binder are coated and dried (the left graph is the overall morphology graph, and the right graph is the local enlarged view), and the surfaces thereof have cracks in different degrees, indicating that the adhesion performance of the above binders is poor. In particular, although the modified dopamine binder introduces disulfide bonds, the molecular weight of dopamine is too small, and the adhesion is relatively weak, which has defects.

[0111] Figure 9 The LSV curve of the electrode for testing the aluminum sheet to which the self-healing binder of the application is directly coated on the current collector as an electrode, and it can be observed from the graph that in the 0-4.5V interval, the current does not obviously rise, indicating that the self-healing binder of the application has no decomposition phenomenon in this interval.

[0112] In summary, combined with Table 1 and the attached Figures 1-8 It can be known that the self-healing binder of the application applied in the non-aqueous aluminum ion system has obvious improvement in the specific discharge capacity compared with the commonly used binder, and due to the formation of the three-dimensional network structure and the introduction of the disulfide bond, the self-healing performance of the binder is obviously improved, and the cycle performance is also significantly improved, at the same time, the binder can timely repair the material, realize self-healing of the material, and further reduce the expansion of cracks.

[0113] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A method for preparing a self-healing adhesive, characterized in that, The method comprises the following steps: S1, dissolving polyglutamic acid in an organic solvent, and sequentially adding a dehydrogenation reagent and a halogen-substituted alkyl, and then centrifuging and rotary evaporating the solution to obtain an intermediate A; S2, dissolving the intermediate A in an organic solvent, and adding the intermediate A dropwise into a thiol-hydroxyl compound under the action of an acidic catalyst, and then filtering and washing the reaction product to obtain an intermediate B; S3, adding an excess of an oxidizing agent into the intermediate B, and then adding a reducing agent to react with the excess oxidizing agent, and then drying the reaction product to obtain a self-healing adhesive; In step S2, the amount of the thiol-hydroxyl compound is 8-12 times the molar amount of the carboxyl group in the intermediate A.

2. The production method according to claim 1, characterized by, In step S1, the dehydrogenation reagent includes any one of potassium carbonate, sodium hydride, potassium hydride, n-butyl lithium and potassium tert-butoxide. The halogen-substituted alkyl includes any one of methyl iodide, methyl chloride, ethyl iodide, 1-iodopropane and butyl iodide.

3. The preparation method according to claim 1, characterized in that, In step S2, the acidic catalyst includes any one of concentrated sulfuric acid, p-toluenesulfonic acid and trifluoromethanesulfonic acid. The thiol-hydroxyl compound includes any one of 2-mercaptoethanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol and hydroxyl-polyethylene glycol-mercapto.

4. The production method according to claim 1, characterized by, In step S2, the reaction is controlled at a temperature of 60-80℃ for 6-10 hours.

5. The method of claim 1, wherein, In step S3, the oxidizing agent includes any one of iodine solution, dimethyl sulfoxide and hydrogen peroxide. The reducing agent includes any one of ascorbic acid, sodium sulfite and sodium bisulfite.

6. A method of preparing a self-healing adhesive, characterized in that, The method comprises the following steps: T1, dissolving polyglutamic acid in an organic solvent, and sequentially adding a dehydrogenation reagent and a halogen-substituted alkyl, and then centrifuging and rotary evaporating the solution to obtain an intermediate A; T2, dissolving the intermediate A and a disulfide bond-amino compound in an organic solvent, and then rotary evaporating and drying the reaction product to obtain a self-healing adhesive; In step T2, the disulfide bond-amino compound includes any one of 4,4'-dithiodianiline and bis(2-aminophenyl)disulfide. The amount of the disulfide bond-amino compound is 1-2 times the molar amount of the carboxyl group in the intermediate A.

7. The method of claim 1 or 6, the self-healing adhesive prepared by the method of claim 1 or 6, use of the self-healing adhesive prepared by the method of claim 1 or 6, characterized in that, The self-healing adhesive is applied in a non-aqueous aluminum ion battery.

Images