In-situ curable electrolyte and electrolyte and battery formed by same

Abstract

The invention discloses an in-situ curable electrolyte, an in-situ curable electrolyte formed by the in-situ curable electrolyte and a battery. The in-situ curable electrolyte comprises an electrolyte and an electrolyte additive, wherein the electrolyte additive comprises a compound A and a compound B, and the compound A is selected from one or more of compounds with a structure as shown in a formula (1); the compound B is selected from one or more of amino-containing compounds; in the formula (1), R3 is a substituent group containing an unsaturated bond. The in-situ curing electrolyte formed by the electrolyte capable of being cured in situ contains a multiple cross-linked network structure formed by interaction of amido and thiolactone, so that the mechanical strength of the gel electrolyte is improved; meanwhile, the gel electrolyte contains disulfide bonds and hydrogen bonds, so that the gel electrolyte is endowed with certain self-repairing capability, and the cycle life of a battery can be prolonged. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to an in-situ curable electrolyte, a gel electrolyte formed therefrom, and a battery. Background Art

[0002] Lithium-ion batteries are widely used in new energy electric vehicles and portable electronic devices due to their advantages such as high energy density, light weight, and small volume. In recent years, with the continuous development of the new energy industry, people's requirements for the energy density and safety performance of secondary lithium batteries have become increasingly high. Traditional lithium-ion batteries are difficult to meet the growing demands of high-power electric vehicles and other large-scale energy storage fields, which has promoted the research and development of new electrode active materials by researchers. High specific energy electrode materials such as silicon anodes and metallic lithium anodes have become research hotspots for further improving the energy density of lithium batteries. However, these electrodes will all generate high volume expansion and contraction during cycling, resulting in great stress inside the battery, leading to the rupture of the battery SEI film, increasing the loss of active lithium and the consumption of electrolyte inside the battery. At the same time, the uneven expansion and contraction of the anode are also prone to uneven deposition of lithium, resulting in the generation of lithium dendrites, ultimately leading to the destruction of the interface, and seriously affecting the stable output of the energy of the solid-state battery and the improvement of the cycle life.

[0003] Gel polymer electrolytes have the advantages of high ionic conductivity of liquid electrolytes, and at the same time have certain mechanical strength, prevent leakage of liquid, and can improve the safety of the battery. Therefore, they have become a major research hotspot. In the case of battery abuse, the gel electrolyte can reduce the volatilization of combustibles, slow down the internal side reactions of the battery and internal short circuits of the battery, and slow down the occurrence of thermal runaway of the battery. However, traditional gel electrolytes do not have self-healing functions. When used in combination with silicon anodes or metallic lithium anodes with high energy density and high expansion and contraction characteristics, there are still problems such as being punctured, resulting in cracking of the anode, interfacial side reactions, and growth of lithium dendrites. Relatively speaking, gel polymer electrolyte materials with self-healing ability can spontaneously heal when damaged, thereby improving the working life and safety of lithium batteries. For example, when a polymer gel with self-healing bonds is damaged by external forces, dynamic reversible bonds will be re-formed at the interface of the crack, promoting the repair of the material structure crack. Therefore, there is an urgent need to develop polymer gel electrolytes with self-healing ability to improve the stability of high energy density lithium batteries and extend their lifespan. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art, such as insufficient self-healing ability of the electrolyte, weak intermolecular force, and insufficient mechanical strength, and to provide an in-situ curable electrolyte, a gel electrolyte formed therefrom, and a battery.

[0005] To achieve the above object, a first aspect of the present invention provides an in-situ curable electrolyte, which comprises an electrolyte and an electrolyte additive; wherein, the electrolyte additive comprises Compound A and Compound B, and Compound A is selected from one or more of the compounds having the structure shown in Formula (1); Compound B is selected from one or more of the compounds containing an amino group;

[0006]

[0007] In Formula (1), R3 is a substituted group containing an unsaturated bond.

[0008] A second aspect of the present invention provides a gel electrolyte, which is obtained by in-situ curing the in-situ curable electrolyte described in the first aspect above.

[0009] A third aspect of the present invention provides a battery, which contains the gel electrolyte described in the second aspect above.

[0010] A fourth aspect of the present invention provides a method for preparing a battery, and the preparation method comprises the following steps:

[0011] Under in-situ curing conditions, Compound A, Compound B and optionally Compound C are mixed in an electrolyte and injected into a dry battery cell composed of at least a positive electrode active material, a negative electrode active material and a separator layer to perform in-situ curing to obtain a battery; wherein, Compound A is selected from one or more of the compounds having the structure shown in Formula (1); Compound B is selected from one or more of the compounds containing an amino group; Compound C is selected from one or more of the compounds containing at least one carbon-carbon double bond;

[0012]

[0013] In Formula (1), R3 is a substituted group containing an unsaturated bond.

[0014] By the above technical solutions, the beneficial technical effects achieved by the present invention are as follows:

[0015] (1) The in-situ curable electrolyte of the present invention contains thiolactone small molecules and compounds containing an amino group. The thiolactone small molecules can interact with the amino group to open the ring and form a reversible cross-linked polymer. Through in-situ curing, an electrolyte containing a multi-cross-linked network structure is formed, which improves the mechanical strength of the gel electrolyte. The formed electrolyte contains both disulfide bonds and hydrogen bonds, endowing the gel electrolyte with certain self-healing ability.

[0016] (2) The gel electrolyte formed by in-situ curing the electrolyte of the present invention not only has the characteristics of high ionic conductivity in the liquid state but also has a certain mechanical strength. At the same time, it contains disulfide bonds, hydrogen bonds and other bonds, endowing it with a certain self-healing function, which can inhibit the cracking problem of the highly swollen negative electrode during use and the problem of the growth of lithium metal dendrites, and can extend the battery cycle life.

[0017] (3) The electrolyte formed by in-situ curing the electrolyte of the present invention can reduce the fluidity and volatility of the electrolyte, avoid the occurrence of liquid leakage. At the same time, in the case of battery abuse, it can reduce the volatilization and leakage of combustibles, hinder the internal side reactions of the battery and the internal short circuit of the battery, and inhibit / slow down the occurrence of thermal runaway of the battery. Description of the Drawings

[0018] Figures 1-3 is the infrared absorption spectra of polymer A0 and polymer A1 prepared in the test example of the present invention;

[0019] Figure 4 is the self-healing photo of the resin sheet of the present invention. Detailed Embodiments

[0020] The endpoints and any values disclosed in this article for a range are not limited to that precise range or value. These ranges or values should be understood to include values close to those ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0021] In the first aspect of the present invention, an in-situ curable electrolyte is provided. The in-situ curable electrolyte includes an electrolyte and an electrolyte additive. Among them, the electrolyte additive includes compound A and compound B. Compound A is selected from one or more of the compounds having the structure shown in formula (1); Compound B is selected from one or more of the compounds containing amino groups;

[0022]

[0023] In formula (1), R3 is a substituted group containing an unsaturated bond.

[0024] The in-situ curable electrolyte of the present invention contains thiolactone small molecules and compounds containing amino groups. The thiolactone small molecules can interact with amino groups to open the ring and form a reversible cross-linked polymer. Through in-situ curing, an electrolyte containing a multi-cross-linked network structure is formed, which improves the mechanical strength of the gel electrolyte. The formed electrolyte contains both disulfide bonds and hydrogen bonds, endowing the gel electrolyte with self-healing ability.

[0025] In some embodiments of the present invention, the compound A is selected from at least one of the compounds having the structures shown in Formulae A-1 to A-15;

[0026]

[0027]

[0028]

[0029] wherein, R is a hydrocarbon group having 1-10 carbon atoms; Z1 is hydrogen or methyl, and Z2 is a saturated alkylene group having 1-9 carbon atoms with or without an alkyl side chain.

[0030] In some embodiments of the present invention, the compound B is selected from one or more of amine substances such as polyethyleneimine, ethylenediamine, propanediamine, butanediamine, 2,5-diaminopentanoic acid, tris(2-aminoethyl)amine, 4,4'-dithiobis(aniline), 2,2'-dithiobis(ethylamine), 4,4'-dithiobis(2-aminobutyric acid), 3,3'-dithiobis(2-aminopropionic acid), dithioformamidine, 2-(2-amino-5-methoxyphenyl)dithio-4-methoxyaniline, and the substance having the structure shown in Formula B-1;

[0031]

[0032] In some embodiments of the present invention, the electrolyte includes a lithium salt and an organic solvent.

[0033] In some preferred embodiments of the present invention, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, lithium difluorooxalate, and lithium difluoroborate.

[0034] In some preferred embodiments of the present invention, the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, or ethyl butyrate, vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and ethylene vinyl carbonate.

[0035] In some embodiments of the present invention, the molar ratio of the compound A based on sulfur element to the compound B based on amino group is 1:0.3-1, preferably 1:0.8-1.

[0036] In some embodiments of the present invention, the electrolyte additive further includes compound C, and compound C is selected from one or more of the compounds containing at least one carbon-carbon double bond.

[0037] In the present invention, compound C can play a role in adjusting the crosslinking density and can be added or not added according to needs.

[0038] In some preferred embodiments of the present invention, compound C is selected from one or more of propylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,3-butanediol diacrylate, neopentyl glycol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tris(2-acryloyloxyethyl) isocyanurate, triallyl cyanurate, cyclohexanedimethanol diacrylate, cyclohexanedimethanol dimethacrylate, 2-[(trimethylsilyl)oxy]-1,3-propanediyl bis(2-methylacrylate), glycerol trimethacrylate, 2-butene-1,4-dimethacrylate, 2,2',2”-nitrilotriethanol trimethacrylate, 2,2,6,6-tetrabromobisphenol A dimethacrylate, 1-methyl-1,2-ethanediyl diacrylate, 2-(phosphoryloxy)propane-1,3-diyl dimethacrylate, 3-methyl-1,5-pentanediyl diacrylate, and 1,2,3-propanetriyl triacrylate.

[0039] In some embodiments of the present invention, the addition amount of the electrolyte additive accounts for 1-20 wt% of the total weight of the in-situ curable electrolyte, preferably 2-10 wt%.

[0040] The second aspect of the present invention provides a gel electrolyte, which is obtained by in-situ curing the in-situ curable electrolyte described in the first aspect above.

[0041] In some embodiments of the present invention, the conditions for in-situ curing include: in the presence of an initiator, the temperature is 40°C - 80°C, preferably 45 - 60°C, and the time is 1 - 24 h, preferably 6 - 18 h.

[0042] In the present invention, the initiator is selected from one or more of azobisisobutyronitrile, benzoyl peroxide, azodiisooctanenitrile, ammonium persulfate, and azobisisobutyramidine hydrochloride.

[0043] In some embodiments of the present invention, the gel electrolyte contains a reversible cross-linked polymer, and the reversible cross-linked polymer contains a structure formed by ring-opening of thiolactone.

[0044] In some preferred embodiments of the present invention, the reversible cross-linked polymer contains amide bonds and disulfide bonds (S-S).

[0045] The gel electrolyte in the present invention contains a multiple cross-linked network structure formed by the interaction of amino groups and thiolactone, which improves the mechanical strength of the gel electrolyte; at the same time, it contains two types of bonds, disulfide bonds and hydrogen bonds, endowing the gel electrolyte with certain self-healing ability.

[0046] In some embodiments of the present invention, the reversible cross-linked polymer contains the structure shown in Formula I:

[0047]

[0048] In Formula I, represents a polymer chain.

[0049] In some embodiments of the present invention, the reversible cross-linked polymer contains the structure shown in Formula II:

[0050]

[0051] In Formula II, R1 and R2 are each independently selected from the group consisting of aliphatic alkylene groups, aromatic alkylene groups, or groups composed of divalent organic chain structures containing heteroatoms; represents a polymer chain; the -SH group can continue to react to form a disulfide bond.

[0052] In some preferred embodiments of the present invention, R1 and R2 are each independently selected from the group consisting of methylene, ethylene, propylene, isopropyl, p-phenylene, m-phenylene, o-phenylene, butyric acid group and groups.

[0053] More preferably, R1 and R2 are selected from the same group.

[0054] In some embodiments of the present invention, the molar ratio of the disulfide bond in the structure of Formula I to the disulfide bond in the structure of Formula II is 1:0 - 1; preferably 1:0.3 - 1.

[0055] The third aspect of the present invention provides a battery, and the battery contains the gel electrolyte described in the second aspect above.

[0056] The fourth aspect of the present invention provides a method for preparing a battery, and the preparation method includes the following steps:

[0057] Under in-situ curing conditions, compound A, compound B and optionally compound C are mixed in an electrolyte and injected into a dry battery cell composed of at least a positive electrode active material, a negative electrode active material and a separator layer to perform in-situ curing to obtain a battery;

[0058] Among them, the compound A is selected from one or more of the compounds having the structure shown in formula (1); the compound B is selected from one or more of the compounds containing an amino group; the compound C is selected from one or more of the compounds containing at least one carbon-carbon double bond;

[0059]

[0060] In formula (1), R3 is a substituted group containing an unsaturated bond.

[0061] In the present invention, "optionally" means that it can be added or not added.

[0062] "Optionally compound C" means that compound C can be used or not used in the preparation process.

[0063] In some embodiments of the present invention, the compound A is selected from at least one of the compounds having the structures shown in formulas A-1 to A-15;

[0064]

[0065]

[0066] Among them, R is a hydrocarbon group containing 1-10 carbon atoms; Z1 is hydrogen or methyl, and Z2 is a saturated alkylene group containing 1-9 carbon atoms with or without an alkyl side chain.

[0067] In some embodiments of the present invention, the compound B is selected from one or more of amine substances such as polyethyleneimine, ethylenediamine, propylenediamine, butylenediamine, 2,5-diaminopentanoic acid, tris(2-aminoethyl)amine, 4,4'-dithiobis(aniline), 2,2'-dithiobis(ethylamine), 4,4'-dithiobis(2-aminobutyric acid), 3,3'-dithiobis(2-aminopropionic acid), dithioformamidine, 2-(2-amino-5-methoxyphenyl)dithio-4-methoxyaniline and the substance having the structure shown in formula B-1;

[0068]

[0069] In some embodiments of the present invention, the compound C is selected from one or more of propylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,3-butanediol diacrylate, neopentyl glycol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tris(2-acryloyloxyethyl) isocyanurate, triallyl cyanurate, cyclohexanedimethanol diacrylate, cyclohexanedimethanol dimethacrylate, 2-[(trimethylsilyl)oxy]-1,3-propanediyl bis(2-methylacrylate), glycerol trimethacrylate, 2-butene-1,4-dimethacrylate, 2,2',2”-nitrilotriethanol trimethacrylate, 2,2,6,6-tetrabromobisphenol A dimethacrylate, 1-methyl-1,2-ethanediyl diacrylate, 2-(phosphonyloxy)propane-1,3-diyl dimethacrylate, 3-methyl-1,5-pentanediyl diacrylate, and 1,2,3-propanetriyl triacrylate.

[0070] In the present invention, the compound A, compound B, compound C, electrolyte, and addition amounts are all the same as those in the first aspect, and for specific details, reference can be made to the previous description, which will not be elaborated herein one by one.

[0071] In some embodiments of the present invention, the in-situ curing conditions include: in the presence of an initiator, the temperature is 40°C - 80°C, preferably 45 - 60°C, and the time is 1 - 24 h, preferably 6 - 18 h.

[0072] The battery prepared by the method of the present invention contains a polymer gel electrolyte with self-healing ability. When the polymer gel with self-healing ability is damaged by external force, dynamic reversible bonds will be re-formed at the interface of the crack, promoting the repair of the crack in the material structure, which can improve the stability of high-energy density lithium batteries, extend their service life, and enhance the safety of the batteries.

[0073] The present invention will be described in detail below through examples.

[0074] In the following examples and comparative examples, unless otherwise specified, all raw materials used are commercially available.

[0075] Button cell performance evaluation: After leaving the prepared 2032 button half-cell standing for 24 h, it was cured at 60 °C for 18 h and then taken out and cooled to room temperature. At room temperature, a charge-discharge cycle test was carried out using a BlueTEC battery test system in the voltage range of 2.75 V - 4.2 V. The test procedure was: charge and discharge at 0.1C / 0.1C for 2 cycles, and then cycle at 0.3C / 0.3C.

[0076] Preparation Example 1

[0077] Dissolve 9.2 g (0.06 mol) of DL-homocysteine thiolactone hydrochloride and 24 g (2.37 mol) of triethylamine in 900 mL of dichloromethane, stir and dissolve in an ice-water bath, slowly add dropwise 9.06 g (0.1 mol) of acryloyl chloride, control the temperature not exceeding 0 °C, and react for 5 h. After the reaction, the organic phase was washed 3 times with saturated brine and dried with anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure, the residue was dissolved in 180 mL of ethyl acetate, filtered through a short silica column, and the filtrate was recrystallized with petroleum ether and filtered to obtain monomer A1.

[0078] Preparation Example 2

[0079] Dissolve 9.2 g (0.06 mol) of DL-homocysteine thiolactone hydrochloride and 24 g (2.37 mol) of triethylamine in 900 mL of dichloromethane, stir and dissolve in an ice-water bath, slowly add dropwise 10.5 g (0.1 mol) of methacryloyl chloride, control the temperature not exceeding 0 °C, and react for 5 h. After the reaction, the organic phase was washed 3 times with saturated brine and dried with anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure, the residue was dissolved in 180 mL of ethyl acetate, filtered through a short silica column, and the filtrate was recrystallized with petroleum ether and filtered to obtain monomer A2.

[0080] Preparation Example 3

[0081] Dissolve 7 g (0.06 mol) of DL-homocysteine thiolactone in dichloromethane, add 9.3 g (0.06 mol) of isocyanatoethyl methacrylate, add 0.001 mol of dibutyltin dilaurate, and stir and react at room temperature for 5 h. After the reaction, the solution was dried with a rotary evaporator to remove most of the dichloromethane, washed with water to remove unreacted monomers and catalysts, and dried to obtain monomer A3.

[0082] Test Example

[0083] Dissolve 9.2 g (0.06 mol) of DL-homocysteine thiolactone hydrochloride and 24 g (2.37 mol) of triethylamine in 900 mL of dichloromethane, stir and dissolve in an ice-water bath, slowly add dropwise 9.06 g (0.1 mol) of acryloyl chloride, control the temperature not to exceed 0 °C, and react for 5 h; wash the organic phase after the reaction 3 times with saturated brine, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure, dissolve the residue in 180 mL of ethyl acetate, filter through a short column of silica gel, and recrystallize the filtrate with petroleum ether, filter to obtain monomer A, named thiolactone acrylamide, and its structural formula is as shown in formula A-7.

[0084] Preparation of polymer A0: Add 4 g of the above-obtained monomer A to 36 g of toluene to prepare a 10 wt% solution, add 40 mg of azobisisobutyronitrile, stir magnetically, and react at a constant temperature of 60 °C for 12 h; after polymerization, precipitate and wash with ethanol 3 times, and dry at 60 °C to obtain polymer A0.

[0085] Preparation of polymer A1: Take an appropriate amount of polymer A0 and dissolve it in tetrahydrofuran to prepare a 10 wt% solution, add n-hexylamine with a molar equivalent to thiolactone, wait until all are dissolved, heat to 60 °C, stir and react for 6 h, precipitate the product with methanol, and dry to obtain polymer A1.

[0086] Infrared characterization of the polymer: Take appropriate amounts of polymer A0 and polymer A1 powders, and use the ATR mode of Nicolet iS50 to test the infrared absorption spectrum, as Figures 1-3 shown. It can be seen from Figure 1 that after the reaction of polymer A0 with n-hexylamine, a mercapto group appears in polymer A1; it can be seen from Figure 2 that the absorption peak of the C=O double bond of polymer A1 undergoes a red shift compared to that of polymer A0, which is due to the stronger electron-donating ability of the N atom on -C(=O)-NH-, proving that the amino group can effectively initiate the ring-opening reaction of thiolactone. In addition, it can be seen from Figure 3 that the peak appearing at 2570 cm -1 in polymer A1 also proves the formation of disulfide bonds during the baking process.

[0087] Self-healing evaluation: Prepare a 20 wt% tetrahydrofuran solution of polymer A0, add an equimolar mass of 4,4'-dithiodianiline, mix evenly, pour it into a PTFE groove, slowly volatilize and dry to form a film, and after the film is basically dry, transfer it to heat and cure at 60 °C for 10 h to obtain a film, as Figure 4The thin films A and B shown in [reference], where thin film B is a blue thin film obtained by adding a small amount of blue ink to the solution. Cut both of them from the middle position, and then splice the A and B samples. Under the action of an external force of 10 g and heating at 60 °C for 30 min, a self-healed thin film can be obtained. The results are shown in Figure 4 the optical pictures, which proves that the binder has certain self-healing ability.

[0088] Example 1

[0089] Preparation of the in-situ curable electrolyte: Add 0.17 g of monomer A1 prepared in Preparation Example 1, 0.13 g of 4,4'-dithiobisbenzeneamine, and 0.01 g of azobisisobutyronitrile to 2.7 g of the electrolyte; among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0090] Battery assembly: Assemble a lithium-ion coin cell in an argon glove box. The positive electrode is composed of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode is metallic lithium. The separator is a 12-μm commercial polypropylene separator. Use the above-prepared in-situ curable electrolyte as the battery electrolyte, with a dosage of 100 μL. After the battery is assembled, let it stand at room temperature for 24 h for sufficient infiltration, and then cure it at 60 °C for 18 h to form a solid-state lithium-ion coin cell.

[0091] Example 2

[0092] Preparation of the in-situ curable electrolyte: Add 0.17 g of monomer A1 prepared in Preparation Example 1, 0.13 g of 4,4'-dithiobisbenzeneamine, and 0.01 g of azobisisobutyronitrile to 1.2 g of the electrolyte; among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0093] Battery assembly: Assemble a lithium-ion coin cell in an argon glove box. The positive electrode is composed of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode is metallic lithium. The separator is a 12-μm commercial polypropylene separator. Use the above-prepared in-situ curable electrolyte as the battery electrolyte, with a dosage of 100 μL. After the battery is assembled, let it stand at room temperature for 24 h for sufficient infiltration, and then cure it at 60 °C for 18 h to form a solid-state lithium-ion coin cell.

[0094] Example 3

[0095] Preparation of in-situ curable electrolyte: 0.17 g of monomer A1 prepared in Preparation Example 1, 0.13 g of 4,4'-dithiobisbenzeneamine, and 0.01 g of azobisisobutyronitrile were added to 0.7 g of electrolyte; wherein, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0096] Battery assembly: A lithium-ion button battery was assembled in an argon glove box. The positive electrode was composed of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode was metallic lithium. A 12-μm commercial polypropylene separator was selected. The above-prepared in-situ curable electrolyte was used as the battery electrolyte, and the dosage was 100 μL. After the battery was assembled, it was left standing at room temperature for 24 h for sufficient infiltration, and then cured at 60 °C for 18 h to form a solid-state lithium-ion button battery.

[0097] Example 4

[0098] Preparation of in-situ curable electrolyte: 0.185 g of monomer A2 prepared in Preparation Example 2, 0.13 g of 4,4'-dithiobisbenzeneamine, and 0.01 g of azobisisobutyronitrile were added to 1.09 g of electrolyte; wherein, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0099] Battery assembly: A lithium-ion button battery was assembled in an argon glove box. The positive electrode was composed of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode was metallic lithium. A 12-μm commercial polypropylene separator was selected. The above-prepared in-situ curable electrolyte was used as the battery electrolyte, and the dosage was 100 μL. After the battery was assembled, it was left standing at room temperature for 24 h for sufficient infiltration, and then cured at 60 °C for 18 h to form a solid-state lithium-ion button battery.

[0100] Example 5

[0101] Preparation of in-situ curable electrolyte: 0.272 g of monomer A3 prepared in Preparation Example 3, 0.13 g of 4,4'-dithiobisbenzeneamine, and 0.01 g of azobisisobutyronitrile were added to 1.608 g of electrolyte; wherein, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0102] Battery Assembly: Assemble lithium-ion coin cells inside an argon glove box. The positive electrode consists of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode is metallic lithium. A 12-μm commercial polypropylene separator is selected. The above-prepared in-situ curable electrolyte is used as the battery electrolyte, with a dosage of 100 μL. After the battery is assembled, it is first left standing at room temperature for 24 h for sufficient infiltration, and then cured at 60 °C for 18 h to form a solid-state lithium-ion coin cell.

[0103] Example 6

[0104] Preparation of In-Situ Curable Electrolyte: Add 0.17 g of monomer A1 prepared in Preparation Example 1, 0.17 g of polyethylene glycol diacrylate (PEGDA, Mn = 1000 g / mol), 0.13 g of 4,4'-dithiobenzidine, and 0.01 g of azobisisobutyronitrile to 1.88 g of electrolyte. Among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0105] Battery Assembly: Assemble lithium-ion coin cells inside an argon glove box. The positive electrode consists of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode is metallic lithium. A 12-μm commercial polypropylene separator is selected. The above-prepared in-situ curable electrolyte is used as the battery electrolyte, with a dosage of 100 μL. After the battery is assembled, it is first left standing at room temperature for 24 h for sufficient infiltration, and then cured at 60 °C for 18 h to form a solid-state lithium-ion coin cell.

[0106] Example 7

[0107] Prepare the in-situ curable electrolyte and assemble the battery respectively according to the method of Example 4.

[0108] The variation is that the addition amounts of substances in the electrolyte preparation are adjusted to: 0.17 g of monomer A1, 0.34 g of polyethylene glycol diacrylate (PEGDA, Mn = 1000 g / mol), 0.13 g of 4,4'-dithiobenzidine, and 0.01 g of azobisisobutyronitrile are added to 2.04 g of electrolyte.

[0109] Example 8

[0110] Prepare the in-situ curable electrolyte and assemble the battery respectively according to the method of Example 4.

[0111] The change is that the amounts of substances added in the preparation of the electrolyte are adjusted to: 0.17 g of monomer A1, 0.17 g of polyethylene glycol diacrylate (PEGDA, Mn = 1000 g / mol), 0.08 g of diethyldithiocarbamate, and 0.01 g of azobisisobutyronitrile are added to 1.68 g of the electrolyte.

[0112] Comparative Example 1

[0113] Prepare the in-situ curable electrolyte and assemble the battery according to the method of Example 1. The difference is that the in-situ curable electrolyte is adjusted to: 0.5 g of polyethylene glycol dimethacrylate (PEGDMA) and 0.01 g of azobisisobutyronitrile are added to 2 g of the electrolyte. Among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0114] Comparative Example 2

[0115] Prepare the in-situ curable electrolyte and assemble the battery according to the method of Example 1. The difference is that the in-situ curable electrolyte is adjusted to: 0.5 g of hexanediol diacrylate and 0.01 g of azobisisobutyronitrile are added to 2 g of the electrolyte. Among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0116] Comparative Example 3

[0117] Assemble a lithium-ion coin cell in an argon glove box. The positive electrode is composed of lithium iron phosphate, Super P, and PVDF in a mass ratio of 94:3:3. The negative electrode is metallic lithium. The separator is a 12-μm commercialized polypropylene separator. 100 μL of the electrolyte is added. Among them, the electrolyte composition is as follows: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, fluoroethylene carbonate (1:1:1:0.3:0.07), 1.5 M LiFSI, 0.5 M LiPF6.

[0118] Electrical performance test method: After the battery is assembled, it is first left standing at room temperature for 24 h for sufficient infiltration. At room temperature, use a Blue Power battery test system to perform charge-discharge cycle tests on the coin cell in a voltage range of 2.5 V - 3.7 V. The test procedure is: charge and discharge at 0.1C / 0.1C for 2 cycles, and cycle at 0.3C / 0.3C.

[0119] Table 1 Test Results

[0120] Number Initial cycle discharge capacity 0.3C-100 cycle capacity retention rate Initial cycle Coulombic efficiency Example 1 170 91％ 82％ Example 2 166 90％ 81％ Example 3 150 93％ 81％ Example 4 159 91％ 84％ Example 5 157 92％ 83％ Example 6 159 91％ 82％ Example 7 170 90％ 81％ Example 8 170 90％ 82％ Comparative Example 1 170 80％ 80％ Comparative Example 2 166 82％ 78％ Comparative Example 3 175 76％ 77％

[0121] As can be seen from the results in Table 1, the cells after in-situ curing have better first-cycle Coulombic efficiency, which proves its effectiveness in improving the side reactions at the negative electrode interface. After 100 cycles, the batteries in-situ cured with the materials obtained in Examples 1-8 of the present invention have higher capacity retention rates compared to Comparative Example 1 and Comparative Example 2 using conventional in-situ curing monomers and Comparative Example 3 without using electrolyte additives. This is because, after introducing the in-situ curing of the materials of the present invention, a uniform network structure is cross-linked, and it contains rich hydrogen bonds and disulfide bonds, endowing the polymer part with certain mechanical strength and good self-healing function, which is beneficial for improving the uneven deposition of lithium and inhibiting the growth of lithium dendrites during the cycling process and improving the side reactions at the interface. In addition, the amide bonds contained in the materials of the present invention have the effect of capturing anions to increase the lithium ion transference number and reducing battery polarization, and the sulfur element contained is beneficial for generating stable CEI and SEI at the positive and negative electrodes, which is also very beneficial for improving the cycling performance of the battery. In Comparative Example 1 and Comparative Example 2, only a chemical cross-linked network structure is formed after in-situ curing, without physical cross-linking and without weak bonds such as disulfide bonds, and the damage of the gel structure during the cycling process will not be automatically repaired, so the improvement of the cycling performance of the cells is not significant. Considering the above characteristics, the in-situ curing material of the present invention finally shows the technical effect of improving the cycling ability of the battery.

[0122] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An in-situ curable electrolyte, characterized in that, The in-situ curable electrolyte includes an electrolyte and an electrolyte additive; wherein, the electrolyte additive includes Compound A and Compound B, and Compound A is selected from one or more of the compounds having the structure shown in Formula (1); Compound B is selected from one or more of the compounds containing an amino group; In Formula (1), R3 is a substituted group containing an unsaturated bond.

2. The in-situ curable electrolyte according to claim 1, wherein, Compound A is selected from at least one of the compounds having the structures shown in Formulae A-1 to A-15; wherein, R is a hydrocarbon group containing 1 to 10 carbon atoms; Z1 is hydrogen or methyl, and Z2 is a saturated alkylene group containing 1 to 9 carbon atoms with or without an alkyl side chain.

3. The in-situ curable electrolyte according to claim 1, wherein, Compound B is selected from one or more of amine substances such as polyethyleneimine, ethylenediamine, propanediamine, butanediamine, 2,5-diaminopentanoic acid, tris(2-aminoethyl)amine, 4,4'-dithiobisbenzenamine, 2,2'-dithiobis(ethylamine), 4,4'-dithiobis(2-aminobutyric acid), 3,3'-dithiobis(2-aminopropionic acid), dithioformamidine, 2-(2-amino-5-methoxyphenyl)dithio-4-methoxyaniline, and the substance having the structure shown in Formula B-1; and / or, the electrolyte includes a lithium salt and an organic solvent; Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, lithium difluorooxalate, and lithium difluoroborate, etc.; Preferably, the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, or ethyl butyrate, vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and ethylene ethyl carbonate; 4. The in-situ curable electrolyte according to claim 1, wherein, The molar ratio of Compound A based on sulfur element to Compound B based on amino group is 1:0.3 - 1, preferably 1:0.8 - 1.

5. The in-situ curable electrolyte according to claim 1, wherein, The electrolyte additive further includes Compound C, and Compound C is selected from one or more of the compounds containing at least one carbon-carbon double bond; Preferably, the compound C is selected from one or more of propylene glycol dimethacrylate, 1,3 - butanediol dimethacrylate, 1,3 - butanediol diacrylate, neopentyl glycol diacrylate, 1,4 - butanediol diacrylate, 1,4 - butanediol dimethacrylate, 1,5 - pentanediol diacrylate, 1,6 - hexanediol dimethacrylate, 1,10 - decanediol diacrylate, 1,10 - decanediol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tris(2 - acryloyloxyethyl) isocyanurate, triallyl cyanurate, cyclohexanedimethanol diacrylate, cyclohexanedimethanol dimethacrylate, 2 - [(trimethylsilyl)oxy] - 1,3 - propanediyl bis(2 - methylacrylate), glycerol trimethacrylate, 2 - butene - 1,4 - dimethacrylate, 2,2',2'' - nitrilotriethanol trimethacrylate, 2,2,6,6 - tetrabromobisphenol A dimethacrylate, 1 - methyl - 1,2 - ethanediyl diacrylate, 2 - (phosphonyloxy)propane - 1,3 - diyl dimethacrylate, 3 - methyl - 1,5 - pentanediyl diacrylate, and 1,2,3 - propanetriyl triacrylate.

6. The in-situ curable electrolyte according to any one of claims 1-5, wherein, The addition amount of the electrolyte additive accounts for 1 - 70 wt% of the total weight of the in - situ curable electrolyte, preferably 2 - 40 wt%.

7. An electrolyte, characterized in that, The electrolyte is obtained by in - situ curing of the in - situ curable electrolyte according to any one of claims 1 - 6.

8. The electrolyte according to claim 7, wherein The conditions for the in - situ curing include: in the presence of an initiator, the temperature is 40°C - 100°C, preferably 60 - 90°C, and the time is 1 - 48 h, preferably 2 - 15 h.

9. An electrolyte, wherein, The in - situ cured electrolyte contains a reversible cross - linked polymer, and the reversible cross - linked polymer contains a structure formed by the ring - opening of thiolactone; Preferably, the reversible cross - linked polymer contains amide bonds and disulfide bonds.

10. The electrolyte according to claim 9, wherein, The reversible cross - linked polymer contains a structure shown in formula I: In Formula I, represents a polymer chain.

11. The electrolyte according to claim 10, wherein, The reversible cross - linked polymer contains a structure shown in formula II: In Formula II, R1 and R2 are each independently selected from the group consisting of an aliphatic alkylene group, an aromatic alkylene group, or a divalent organic chain structure containing a heteroatom; represents a polymer chain; the -SH group can continue to react to form a disulfide bond; Preferably, R1 and R2 are each independently selected from the group consisting of methylene, ethylene, propylene, isopropylidene, p-phenylene, m-phenylene, o-phenylene, butyric acid group and groups consisting of; More preferably, R1 and R2 are selected from the same group.

12. The electrolyte according to claim 11, wherein, The molar ratio of the disulfide bond in the structure of formula I to the disulfide bond in the structure of formula II is 1:0 - 1; preferably 1:0.3 - 1.

13. A battery, characterized in that, The battery contains the electrolyte according to any one of claims 7 - 12.

14. A method for preparing a battery, characterized in that, The preparation method includes the following steps: Under the conditions of in - situ curing, compound A, compound B and optionally compound C are mixed in the electrolyte, and then injected into a dry battery cell composed of at least a positive electrode active material, a negative electrode active material, and a separator layer, and in - situ curing is carried out to obtain the battery; Among them, the compound A is selected from one or more of the compounds having the structure shown in formula (1); the compound B is selected from one or more of the compounds containing amino groups; the compound C is selected from one or more of the compounds containing at least one carbon - carbon double bond; In formula (1), R3 is a substituted group containing an unsaturated bond.

15. The preparation method according to claim 14, wherein The compound A is selected from at least one of the compounds having the structures shown in formulas A-1 to A-15; wherein, R is a hydrocarbon group having 1 to 10 carbon atoms; Z1 is hydrogen or methyl, and Z2 is a saturated alkylene group having 1 to 9 carbon atoms with or without an alkyl side chain; and / or, the compound B is selected from one or more of amine substances such as polyethyleneimine, ethylenediamine, propylenediamine, butylenediamine, 2,5-diaminopentanoic acid, tris(2-aminoethyl)amine, 4,4'-dithiobis(aniline), 2,2'-dithiobis(ethylamine), 4,4'-dithiobis(2-aminobutyric acid), 3,3'-dithiobis(2-aminopropionic acid), dithioformamidine, 2-(2-amino-5-methoxyphenyl)dithio-4-methoxyaniline, and the substance having the structure shown in formula B-1; and / or, the compound C is selected from one or more of propylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,3-butanediol diacrylate, neopentyl glycol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tris(2-acryloyloxyethyl) isocyanurate, triallyl cyanurate, cyclohexanedimethanol diacrylate, cyclohexanedimethanol dimethacrylate, 2-[(trimethylsilyl)oxy]-1,3-propanediyl bis(2-methylacrylate), glycerol trimethacrylate, 2-butene-1,4-dimethacrylate, 2,2',2”-nitrilotriethanol trimethacrylate, 2,2,6,6-tetrabromobisphenol A dimethacrylate, 1-methyl-1,2-ethanediyl diacrylate, 2-(phosphonyloxy)propane-1,3-diyl dimethacrylate, 3-methyl-1,5-pentanediyl diacrylate, and 1,2,3-propanetriyl triacrylate.

16. The preparation method according to claim 14 or 15, wherein The in-situ curing conditions include: in the presence of an initiator, the temperature is 40°C - 100°C, preferably 60 - 90°C, and the time is 1 - 48 h, preferably 2 - 15 h.

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