A gel electrolyte composition and use thereof

Abstract

This invention relates to a gel electrolyte composition and its application. The gel electrolyte composition comprises acrylate monomers, polyethylene oxide, a bifunctional alkoxysilane crosslinking agent, an initiator, a lithium salt, and a solvent, wherein the bifunctional alkoxysilane crosslinking agent is an alkoxysilane with terminal unsaturated bonds. The gel electrolyte composition of this invention has extremely low viscosity, enabling "normal electrolyte injection" indistinguishable from liquid electrolytes, perfectly wetting thick electrodes, seamlessly integrating with existing battery production lines, and showing excellent industrialization prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary battery materials, in particular to a gel electrolyte composition and application thereof. BACKGROUND

[0002] Energy density and safety are the core contradictions of the development of secondary batteries. Liquid electrolyte is easy to leak and easy to burn and explode, while the all-solid-state electrolyte faces the problems of low room temperature conductivity and large solid-solid interface impedance. As a compromise, gel electrolyte (GPE) has high ionic conductivity of liquid electrolyte and safety of solid-state electrolyte, and has become a research hotspot.

[0003] Existing gel electrolyte technologies are mainly divided into two categories: Ex-situ preparation method: gel film is prepared in advance and then assembled into a battery. The electrolyte prepared by this method has poor interface contact with the electrode, and large interface impedance.

[0004] In-situ preparation method: polymer precursor solution is injected into the battery and then polymerization is induced to form a gel. This method has good interface contact, but has the following significant defects: the in-situ polymerization precursor solution of the existing technology usually has high viscosity (such as containing a large amount of polymer) and poor flowability, and cannot fully infiltrate commercial thick electrodes and complex wound battery cells, and is not compatible with the liquid injection process of existing battery production lines, which is difficult to industrialize.

[0005] Therefore, it is of great industrial value to develop a new type of electrolyte. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of high viscosity, poor wettability and incompatibility with commercial battery manufacturing methods of the electrolyte in the prior art, and to provide a gel electrolyte composition and application thereof.

[0007] In a first aspect, the present application provides a gel electrolyte composition, comprising an acrylate monomer, a polyethylene oxide, a bifunctional alkoxysilane crosslinking agent, an initiator, a lithium salt and a solvent, wherein the bifunctional alkoxysilane crosslinking agent is an alkoxysilane having an end group unsaturated bond.

[0008] Further, the bifunctional alkoxysilane crosslinking agent has a structure shown in Formula 1: Formula 1 wherein R1, R2, R3 are the same or different, and each is independently selected from H, substituted or unsubstituted C1-C20 alkyl; R4, R5, and R6 may be the same or different, and each is independently selected from H, halogen, cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C1-C30 heteroaryl; The substituents are selected from any one or a combination of at least two of the following: deuterium, halogen, cyano, nitro, C1-C20 alkyl, C1-C20 alkoxy, C3-C20 cycloalkyl, C6-C30 aryl, and C3-C30 heteroaryl. n is an integer from 1 to 10, preferably an integer from 1 to 5.

[0009] Furthermore, R1, R2, and R3 are identical and each is independently selected from H, substituted or unsubstituted C1-C5 alkyl groups; and / or R4, R5, and R6 may be the same or different, and each is independently selected from H, halogen, cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C5 alkyl; and / or The substituents are selected from deuterium, halogen, cyano, nitro, and C1-C5 alkyl.

[0010] Furthermore, the bifunctional alkoxysilane crosslinking agent is selected from γ-(methacryloyloxy)propyltrimethoxysilane; and / or The acrylate monomers are selected from methyl methacrylate and / or ethyl acrylate; and / or The initiator is selected from thermal initiators, preferably from azobisisobutyronitrile and / or benzoyl peroxide, and / or The lithium salt is selected from lithium bis(trifluoromethanesulfonylimide) and / or lithium hexafluorophosphate; and / or The solvent is selected from organic solvents, preferably carbonate solvents, and more preferably one or more selected from ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and / or The weight-average molecular weight of the polyoxyethylene is 10,000 to 300,000.

[0011] Further, based on the total weight of the gel electrolyte composition as 100%, the content of the acrylate monomer is 5 wt% to 25 wt%, the content of the polyethylene oxide is 1 wt% to 8 wt%, the content of the bifunctional alkoxysilane crosslinking agent is 0.5 wt% to 25 wt%, the content of the initiator is 0.1 wt% to 1.5 wt%, the content of the lithium salt is 8 wt% to 35%, and the balance is the solvent.

[0012] Furthermore, the viscosity of the gel electrolyte composition at 25°C is less than 20 mPa·s.

[0013] In a second aspect, the present invention provides a gel electrolyte, which is formed by reacting the gel electrolyte composition described in the first aspect.

[0014] Furthermore, the preparation method of the gel electrolyte includes: injecting the gel electrolyte composition into the battery and reacting it.

[0015] Thirdly, the present invention provides a secondary battery comprising the gel electrolyte described in the second aspect.

[0016] Furthermore, the secondary battery is a lithium battery.

[0017] Fourthly, the present invention provides a method for preparing a secondary battery, comprising: (1) Install the battery cell containing the positive electrode, separator and negative electrode into the battery casing; (2) The gel electrolyte composition described in the first aspect is injected into the battery casing to wet the positive electrode, negative electrode and separator, and then pre-charged to obtain the formed battery; (3) React the formed battery to obtain the secondary battery.

[0018] Furthermore, the reaction temperature is 60~85℃, and / or The reaction time is 2 to 10 hours.

[0019] Fifthly, the present invention provides a battery module comprising the secondary battery described in the third aspect or the secondary battery prepared by the preparation method described in the fourth aspect.

[0020] In a sixth aspect, the present invention provides a battery pack comprising the battery module described in the fifth aspect.

[0021] In a seventh aspect, the present invention provides an electrical device comprising a secondary battery as described in the third aspect or a secondary battery prepared by the preparation method described in the fourth aspect, wherein the secondary battery is used as a power source for the electrical device.

[0022] Furthermore, the electrical device includes one or more of the following: electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, electric bicycle, electric scooter, electric truck, and electric boat.

[0023] The present invention has the following beneficial effects: The gel electrolyte composition of this application has extremely low viscosity, which can achieve "normal liquid injection" indistinguishable from liquid electrolyte, perfectly wet thick electrodes, and seamlessly connect to existing battery production lines, with excellent industrialization prospects. This is in stark contrast to existing high-viscosity in-situ polymerization technology.

[0024] This application describes a one-step method to simultaneously form a gel electrolyte with an organic-inorganic hybrid network, which combines high strength (inorganic phase, anti-dendritic), high ionic conductivity (organic phase and liquid solvent) and excellent thermal / chemical stability, with performance far exceeding that of pure organic gels or physical blend composites.

[0025] This application ensures the formation of a high-quality SEI film through a "formation-then-gel" method, which improves the initial efficiency and lifespan of the secondary battery; the final product is in a gel state, which completely eliminates the risk of leakage and combustion of liquid electrolyte and passes the needle penetration test. Attached Figure Description

[0026] Figure 1 This is the gel electrolyte composition of Example 1 of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] Definitions and general terms Unless otherwise stated, the terms used in the specification and claims of this invention have the following definitions.

[0030] Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0031] It should be further recognized that certain features of the present invention are described in multiple independent embodiments for clarity, but can also be provided in combination in a single embodiment. Conversely, various features of the present invention are described in a single embodiment for brevity, but can also be provided separately or in any suitable sub-combination.

[0032] Unless otherwise stated, all scientific and technical terms used in this invention have the same meaning as commonly understood by those skilled in the art to which this invention pertains. All patents and published publications related to this invention are incorporated herein by reference in their entirety.

[0033] Unless otherwise specified or there is an obvious conflict in the context, the articles "a", "an", and "the" used herein are intended to include "at least one" or "one or more". Thus, these articles used herein refer to articles for one or more (i.e., at least one) objects. For example, "a component" refers to one or more components, that is, there may be more than one component considered to be adopted or used in the implementation of the said embodiment.

[0034] In the present invention, for the expression of chemical elements, unless otherwise specified, the concept of isotopes with the same chemical properties is included. For example, hydrogen (H) includes 1 H (protium), 2 H (deuterium, D), 3 H (tritium, T), etc.; carbon (C) includes 12C, 13C, etc.

[0035] In the present invention, unless otherwise specified, the heteroatoms of heteroaryl are selected from N, O, S, P, B, Si or Se, preferably N, O or S.

[0036] In the present invention, "each independently" means that when its subject has multiple entities, they can be the same or different from each other.

[0037] In the present invention, the expression Ca-Cb represents that the group has a carbon atom number of a - b. Unless otherwise specified, the carbon atom number does not include the carbon atoms of substituents.

[0038] In the present invention, the C1-C20 can all be C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 or C19, etc.

[0039] In the present invention, the C3-C20 can all be C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 or C19, etc.

[0040] In this invention, C6-C30 can all be C6, C9, C10, C12, C14, C16, C18, C20, C22, C24, C26 or C28, etc.

[0041] In this invention, C3-C30 can all be C3, C4, C5, C6, C9, C10, C12, C14, C16, C18, C20, C22, C24, C26 or C28, etc.

[0042] The term "comprising" is an open-ended expression, meaning it includes the contents specified in this invention, but does not exclude other aspects.

[0043] As described in this invention, the compounds of this invention may optionally be substituted with one or more substituents, such as the general formula compounds above, or as the specific examples, subclasses, and classes of compounds included in this invention as described in the embodiments. It should be understood that the term "optionally substituted" is used interchangeably with the term "substituted or unsubstituted." Generally, the term "optionally," whether or not preceding the term "substituted," refers to the substitution of one or more hydrogen atoms selected from the given structure by a specific substituent. Unless otherwise indicated, an optional substituent group may have one substituent substituted at each substituted position of the group. When more than one position in the given structural formula is substituted by one or more substituents selected from a specific group, the substituents may be substituted at the same or different positions. The substituents mentioned therein can be, but are not limited to, deuterium, hydroxyl, amino, halogen, cyano, aryl, heteroaryl, alkoxy, alkyl, mercapto, nitro, oxo (=O), carboxyl, hydroxy-substituted alkoxy, hydroxy-substituted alkyl-C (=O), alkyl-C (=O), alkyl-S (=O), alkyl-S (=O)2-, hydroxy-substituted alkyl-S (=O), hydroxy-substituted alkyl-S (=O)2, carboxyalkoxy, etc.

[0044] As used in this invention, the term "alkyl" refers to a saturated straight-chain or branched monovalent hydrocarbon group having 1-30 carbon atoms, or 1-20 carbon atoms, or 1-10 carbon atoms, or 1-6 carbon atoms, or 1-4 carbon atoms, or 1-3 carbon atoms, wherein the alkyl group may be independently and optionally substituted by one or more substituents described in this invention. Examples of alkyl groups include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), n-propyl (n-Pr, -CH2CH2CH3), isopropyl (i-Pr, -CH(CH3)2), n-butyl (n-Bu, -CH2CH2CH2CH3), isobutyl (i-Bu, -CH2CH(CH3)2), sec-butyl (s-Bu, -CH(CH3)CH2CH3), tert-butyl (t-Bu, -C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl-1- Butyl (-CH2CH(CH3)CH2CH3), n-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3) ), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3), n-heptyl, n-octyl, etc. The term "alkyl" and its prefix "alkane" are used herein to refer to both straight-chain and branched saturated carbon chains. The term "alkane" is used herein to refer to a saturated divalent hydrocarbon group obtained by eliminating two hydrogen atoms from a straight-chain or branched saturated hydrocarbon; examples of such groups include, but are not limited to, methylene, methine, methinepropyl, etc.

[0045] The term "alkoxy" as used in this invention refers to an alkyl group, as defined herein, that is attached to the main carbon chain by an oxygen atom. Examples of such alkyl groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, etc. Furthermore, the alkoxy group may be substituted or unsubstituted, wherein the substituent may be, but is not limited to, hydroxyl, amino, halogen, cyano, alkoxy, alkyl, alkenyl, alkynyl, mercapto, nitro, etc.

[0046] The term "cycloalkyl" refers to a monovalent or polyvalent, non-aromatic, saturated or partially unsaturated ring that does not contain heteroatoms, including monocyclic rings of 3-12 carbon atoms or bicyclic rings of 7-12 carbon atoms. Bicyclic carbocyclic rings with 7-12 atoms can be bicyclic [4,5], [5,5], [5,6], or [6,6] systems, while bicyclic carbocyclic rings with 9 or 10 atoms can be bicyclic [5,6] or [6,6] systems. Suitable cyclic aliphatic groups include, but are not limited to, cycloalkyl, cycloalkenyl, and cycloynyl groups. Examples of cyclic aliphatic groups include, but are by no means limited to, cyclopropyl, cyclobutyl, cyclopentyl, 1-cyclopentyl-1-enyl, 1-cyclopentyl-2-enyl, 1-cyclopentyl-3-enyl, cyclohexyl, 1-cyclohexyl-1-enyl, 1-cyclohexyl-2-enyl, 1-cyclohexyl-3-enyl, cyclohexadienyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, etc. Furthermore, the "cyclic aliphatic group" or "carbocyclic", "carbocyclic group", and "cycloalkyl" may be substituted or unsubstituted, wherein the substituent may be, but is not limited to, hydroxyl, amino, halogen, cyano, aryl, heteroaryl, alkoxy, alkylamino, alkyl, alkenyl, alkynyl, heterocyclic, mercapto, nitro, aryloxy, hydroxy-substituted alkoxy, hydroxy-substituted alkyl-C(=O), alkyl-C(=O), alkyl-S(=O), alkyl-S(=O)2-, hydroxy-substituted alkyl-S(=O), hydroxy-substituted alkyl-S(=O)2, carboxyalkoxy, etc.

[0047] In this invention, unless otherwise specified, the term C6-C30 aryl (C6-C30 aromatic ring) includes monocyclic aryl and fused-ring aryl; the monocyclic aryl means that the group contains at least one phenyl group, and when it contains at least two phenyl groups, the phenyl groups are linked by a single bond, exemplarily including but not limited to: phenyl, biphenyl, terphenyl, tetraphenyl, etc.; the fused-ring aryl means that the group contains at least two rings (and at least one ring is an aromatic ring), and the rings share two adjacent carbon atoms that are fused together, exemplarily including but not limited to: naphthyl, anthraceneyl, phenanthryl, indene, fluorenyl and their derivatives (9,9-dimethyl... Aryl fluorenyl, 9,9-diethylfluorenyl, 9,9-dipropylfluorenyl, 9,9-dibutylfluorenyl, 9,9-dipentylfluorenyl, 9,9-dihexylfluorenyl, 9,9-diphenylfluorenyl, 9-methyl-9-phenylfluorenyl, 9,9-dinaphthylfluorenyl, spirodifluorenyl, benzo[A]fluorenyl, benzo[B]fluorenyl, benzo[C]fluorenyl, fluoranyl, triphenylene, pyrene, peryl, phenyl, tetraphenyl, acenaphthene, benzo[acenaphthene], etc. It should be noted that monocyclic aryl and fused-ring aryl groups linked by single bonds also fall under the category of aryl groups, such as phenylnaphthyl, naphthylphenyl, and binaphthyl.

[0048] In this invention, unless otherwise specified, the term C3-C30 heteroaryl (C3-C30 heteroaryl ring) includes monocyclic heteroaryl or fused-ring heteroaryl. A monocyclic heteroaryl means that the molecule contains at least one heteroaryl group. When the molecule contains one heteroaryl group and other groups (such as aryl, heteroaryl, etc.), the heteroaryl group and other groups are connected by a single bond, exemplarily including but not limited to: pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furanyl, thiophene, pyrroleyl, bipyridyl, phenylpyridinyl, pyridylphenyl, etc. The term "fused-ring heteroaryl" refers to a molecule containing at least one aromatic heterocycle and one aromatic ring (aromatic heterocycle or aromatic ring), which share two adjacent fused groups. Exemplary examples include, but are not limited to: quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothiopheneyl, isobenzofuranyl, isobenzothiopheneyl, indolyl, dibenzofuranyl, benzonaphthofuranyl (benzo[B]naphtho[2,3-D]furanyl, benzo[B]naphtho[1,2-D) Furanyl, benzo[B]naphtho[2,1-D]furanyl), dibenzothiophenyl, benzo[B]naphtho[2,3-D]thiophenyl, benzo[B]naphtho[1,2-D]thiophenyl, benzo[B]naphtho[2,1-D]thiophenyl, carbazoleyl and its derivatives (N-phenylcarbazoleyl, N-naphthylcarbazoleyl, benzocarbazoleyl, dibenzocarbazoleyl, indole-carbazoleyl, azacarbazoleyl, etc.), acridineyl, phenothiazinyl, phenotoxazinyl, hydrogenated acridineyl, etc.

[0049] In the compounds mentioned in this invention, hydrogen atoms can be partially or completely replaced by deuterium. Other atoms such as carbon and nitrogen can also be replaced by their other stable isotopes. Substitution with other stable isotopes in the compounds may be preferred due to their ability to enhance device efficiency and stability.

[0050] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0051] In a first aspect, the present invention provides a gel electrolyte composition comprising an acrylate monomer, polyethylene oxide, a bifunctional alkoxysilane crosslinking agent, an initiator, a lithium salt, and a solvent, wherein the bifunctional alkoxysilane crosslinking agent is an alkoxysilane having terminal unsaturated bonds.

[0052] The bifunctional alkoxysilane crosslinking agent of this application contains both polymerizable olefin bonds and hydrolyzable alkoxy groups, serving as a "bridging" molecule for simultaneous organic-inorganic hybrid crosslinking. Utilizing the bifunctional nature of this crosslinking agent, organic polymerization and inorganic condensation are simultaneously achieved through one-step thermal initiation, forming a chemically bonded interpenetrating hybrid network. Compared to traditional techniques for introducing inorganic phases (simply adding nanoparticles), this application achieves the introduction of inorganic phases through molecular-level chemical bonding using a bifunctional alkoxysilane crosslinking agent, solving the problems of aggregation and interfacial compatibility, and forming a unique hybrid network structure. Compared to silane crosslinking agents containing only alkoxy groups, such as (3-chloropropyl)trimethoxysilane, the bifunctional alkoxysilane crosslinking agent forms a gel in a shorter time.

[0053] Specifically, acrylate monomers undergo polymerization under the action of an initiator to obtain polyacrylic acid and unreacted acrylate monomers. The bifunctional alkoxysilane crosslinking agent of this application reacts with polyacrylate to achieve silane grafting modification of polyacrylate, improving the weather resistance, scratch resistance, and compatibility with inorganic materials of polyacrylate. Simultaneously, the bifunctional alkoxysilane crosslinking agent of this application also reacts with polyethylene oxide. Polyethylene oxide is characterized by strong hydrophilicity and easy crystallization. After grafting with the bifunctional alkoxysilane crosslinking agent of this application, hydrophobic siloxy groups can be introduced, improving its water resistance and thermal stability. Simultaneously, the silyl groups can serve as crosslinking sites. Furthermore, the alkoxy groups of the bifunctional alkoxysilane crosslinking agent of this application undergo hydrolysis-condensation reactions to achieve crosslinking and curing of the system, thereby forming a three-dimensional crosslinked network, improving its hardness, tensile strength, and solvent resistance, overcoming the shortcomings of poor impact resistance of polyacrylate or acrylate monomers and the easy solubility of polyethylene oxide.

[0054] In summary, this application achieves ultra-low viscosity and high wettability of the precursor solution through a unique combination of low-viscosity monomers (acrylate monomers), polyethylene oxide (PEO), and bifunctional alkoxysilane crosslinking agents.

[0055] In some embodiments, the bifunctional alkoxysilane crosslinking agent has the structure shown in Formula 1: Formula 1 Wherein, R1, R2, and R3 may be the same or different, and each is independently selected from H, substituted or unsubstituted C1-C20 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.) alkyl groups; R4, R5, and R6 may be the same or different, and each is independently selected from H, halogen, cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyanate, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C20 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.) alkyl, substituted or unsubstituted C1-C20 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, etc.) Alkoxy groups (C3-C20, etc.), substituted or unsubstituted C3-C20 cycloalkyl groups (e.g., C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.), substituted or unsubstituted C6-C30 groups (e.g., C6, C8, C10, C12, C14, C16, C18, C20, C22, C24, C26, C28, C30, etc.), substituted or unsubstituted C1-C30 groups (e.g., C2, C4, C6, C8, C10, C12, C14, C16, C18, C20, C22, C24, C26, C28, C30, etc.), heteroaryl groups; The substituents are selected from deuterium, halogen, cyano, nitro, C1-C20 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.) alkyl, C1-C20 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.) alkoxy, C3-C20 (e.g., C 3. Cycloalkyl groups (C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, etc.), aryl groups (C6-C30, e.g., C6, C8, C10, C12, C14, C16, C18, C20, C22, C24, C26, C28, C30, etc.), and heteroaryl groups (C3-C30, e.g., C2, C4, C6, C8, C10, C12, C14, C16, C18, C20, C22, C24, C26, C28, C30, etc.); n is an integer from 1 to 10, for example, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. In some implementations, n is an integer from 1 to 5.

[0056] In some embodiments, R1, R2, and R3 are the same and each is independently selected from H, substituted or unsubstituted C1-C5 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, etc. In some embodiments, R1, R2, and R3 are all selected from unsubstituted C1-C5 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, etc.

[0057] In some embodiments, R4, R5, and R6 may be the same or different, and each is independently selected from H, halogens (such as F, Cl, Br, etc.), cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C5 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, etc. In some embodiments, R4, R5, and R6 may be the same or different, and each is independently selected from H, halogens (such as F, Cl, Br, etc.), and unsubstituted C1-C5 alkyl groups.

[0058] In some embodiments, the substituents are selected from deuterium, halogen, cyano, nitro, and C1-C5 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, etc.

[0059] In some embodiments, the bifunctional alkoxysilane crosslinking agent is selected from γ-(methacryloyloxy)propyltrimethoxysilane (KH570).

[0060] In some embodiments, this application does not have particular limitations on the type of acrylate monomers. Any acrylate monomer that can form a gel can be used in this application. For example, the acrylate monomers include, but are not limited to, methyl methacrylate (MMA) and ethyl acrylate. Acrylate monomers are the main building blocks of the organic polymer network in the precursor electrolyte. In order to ensure the low viscosity of the system, this application prefers the above-mentioned low-viscosity monomers.

[0061] The key role of polyethylene oxide (PEO) is to provide lithium ion coordination sites. In order to ensure that the viscosity of the gel electrolyte composition is at an ultra-low level, in some embodiments, the weight-average molecular weight of the polyethylene oxide is 10,000 to 300,000.

[0062] This application does not impose any particular limitation on the initiator; any initiator commonly used in the art for thermally triggered polymerization can be used in this application. In some embodiments, the initiator is selected from thermal initiators. In some embodiments, the initiator includes, but is not limited to, azobisisobutyronitrile (AIBN) and / or benzoyl peroxide.

[0063] This application does not impose any particular limitation on lithium salts; any lithium salt commonly used in the art can be used in this application. In some embodiments, the lithium salt may be lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate, etc.

[0064] This application does not impose any particular limitation on the type of solvent; conventional liquid electrolyte solvents are sufficient. In some embodiments, the solvent is selected from organic solvents, preferably carbonate solvents, and more preferably one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC). In some embodiments, the solvent is selected from a combination of ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC). In some embodiments, the mass ratio of ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC) in the solvent is 1:1:1.

[0065] In some embodiments, the content of the acrylate monomer is 5 wt% to 25 wt% based on 100% of the total weight of the gel electrolyte composition, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% or any value between them.

[0066] To ensure the ultra-low viscosity of the gel electrolyte composition, the content of polyethylene oxide should not be too high. In some embodiments, the content of polyethylene oxide, based on 100% of the total weight of the gel electrolyte composition, is 1 wt% to 8 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, or any value between them.

[0067] In some embodiments, the content of the bifunctional alkoxysilane crosslinking agent is 0.5 wt% to 25 wt%, for example, 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.1 wt%, 1.3 wt%, 1.5 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or any value between them, based on 100% of the total weight of the gel electrolyte composition.

[0068] In some embodiments, the initiator content, based on 100% of the total weight of the gel electrolyte composition, is 0.1 wt% to 1.5 wt%, for example, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.1 wt%, 1.3 wt%, 1.5 wt%, or any value between them. To avoid excessive crosslinking of the acrylate monomers, the initiator concentration must be maintained within the above range; excessive initiator can easily lead to gelation of the acrylate monomers.

[0069] In some embodiments, the lithium salt content is 8 wt% to 35% based on 100% of the total weight of the gel electrolyte composition, for example, 8 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt% or any value between them.

[0070] In some embodiments, the total weight of the gel electrolyte composition is 100%, with the remainder being the solvent.

[0071] By controlling the amount of the gel electrolyte composition within the above-mentioned range, this application can ensure a certain ionic conductivity while preventing the viscosity from becoming too high.

[0072] In some embodiments, the viscosity of the gel electrolyte composition at 25°C is less than 20 mPa·s.

[0073] Secondly, this invention provides a gel electrolyte, formed by reacting the gel electrolyte composition described in the first aspect. The gel electrolyte of this application possesses both high ionic conductivity and safety, as well as excellent thermal / chemical stability. During preparation, it can be injected and wetted like a liquid electrolyte, subsequently forming a high-performance gel network. It is fully compatible with existing battery production lines and has significant industrial value.

[0074] In some embodiments, the preparation method of the gel electrolyte includes: injecting the gel electrolyte composition described in the first aspect into the battery for reaction. This application employs an in-situ preparation method to obtain the gel electrolyte, which provides good interfacial contact.

[0075] Thirdly, the present invention provides a secondary battery comprising the gel electrolyte described in the second aspect. The secondary battery prepared using the above-described gel electrolyte exhibits good initial efficiency and cycle life.

[0076] In some embodiments, the secondary battery is a lithium battery.

[0077] Fourthly, the present invention provides a method for preparing a secondary battery, comprising: (1) Install the battery cell containing the positive electrode, separator and negative electrode into the battery casing; (2) The precursor electrolyte described in the first aspect is injected into the battery casing to wet the positive electrode, negative electrode and separator, and then pre-charged to obtain the formed battery; (3) React the formed battery to obtain the secondary battery.

[0078] This application involves wetting the electrodes and separator with the precursor electrolyte, followed by pre-charging (i.e., formation), and then reacting the formed battery (thermally initiated free radical polymerization and sol-gel reaction) to prepare a gel electrolyte, thereby further obtaining the secondary battery. This application combines excellent wettability with a perfect interface (SEI) and ultimate safety through the pathway of electrolyte injection, formation, and thermal gelation.

[0079] Specifically, the following reaction occurs in step (3): Thermally initiated free radical polymerization: The initiator in the precursor electrolyte decomposes, initiating the copolymerization of olefin bonds between acrylate monomers and bifunctional alkoxysilane crosslinking agents to form an organic polymer network.

[0080] Sol-gel reaction: Trace amounts of moisture in the system (from the environment or reagents) cause the alkoxy groups (such as methoxy groups) of the bifunctional alkoxysilane crosslinking agent (such as KH570) to hydrolyze and condense, forming an inorganic Si-O-Si network.

[0081] The two reactions above proceed simultaneously, forming an interpenetrating hybrid network in which the organic and inorganic phases are connected by chemical bonds (C-Si-O) in a one-step process, thus firmly locking the liquid component and obtaining the gel electrolyte described in the second aspect.

[0082] Furthermore, the process of first forming and then gelling ensures the formation of a high-quality SEI film, improving the battery's initial efficiency and lifespan. At the same time, the gel-state electrolyte completely eliminates the risk of leakage and combustion of the liquid electrolyte, and the prepared secondary battery passed the nail penetration test.

[0083] In some embodiments, the pre-charging step (i.e., the formation step) in step (2) can involve sealing the battery described in step (1) and performing a small-current pre-charge in a liquid environment using conventional methods. Through the formation step, a complete and stable solid electrolyte interphase (SEI) film can be formed on the negative electrode surface. In some embodiments, the pre-charging current can be 0.01C-0.1C, for example, 0.01C, 0.03C, 0.05C, 0.07C, 0.09C, 0.1C, or any value between them.

[0084] In some implementations, both the positive and negative electrodes are conventional materials recognized within the industry. The positive electrode active material can be a binary or ternary active material, such as NCM811. The negative electrode active material can be silicon-carbon anode, natural graphite, artificial graphite, composite graphite, etc. The conductive agents in the positive and negative electrode sheets can be Super-P, acetylene black, KS-6, CNT, or graphene, etc. The binders in the positive and negative electrode sheets can be polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, etc. The ratio of active material, conductive agent, and binder in the positive and negative electrode sheets can be 5~10:0.1-5:1. The separator can be PP, PE, etc. The positive electrode current collector can be aluminum foil, composite aluminum foil, etc. The negative electrode current collector can be copper foil.

[0085] In some embodiments, the reaction is carried out in an oven.

[0086] In some embodiments, the reaction temperature is 60-85°C, for example 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or any value between them.

[0087] In some implementations, the reaction time is 2 to 10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours or any value between them.

[0088] Fifthly, the present invention provides a battery module comprising the secondary battery described in the third aspect or the secondary battery prepared by the preparation method described in the fourth aspect.

[0089] In a sixth aspect, the present invention provides a battery pack comprising the battery module described in the fifth aspect.

[0090] In a seventh aspect, the present invention provides an electrical device comprising a secondary battery as described in the third aspect or a secondary battery prepared by the preparation method described in the fourth aspect, wherein the secondary battery is used as a power source for the electrical device.

[0091] In some embodiments, the electrical device includes one or more of the following: electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, electric bicycle, electric scooter, electric truck, and electric boat.

[0092] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0093] In this application, room temperature refers to 20-35℃.

[0094] Example 1: (Preparation of a pouch cell) Preparation of the electrolyte composition: In a glove box, dissolve MMA (15 wt%), PEO (5 wt%, Mw=200 kJ), KH570 (15 wt%), AIBN (0.5 wt%), and LiTFSI (10 wt%) in EC / DMC / EMC (1:1:1, 54.5 wt%) and stir until clear. The viscosity was measured to be 15 mPa·s. The fluidity and wettability of the electrolyte composition are as follows. Figure 1 As shown.

[0095] Battery assembly: Using NCM811 as the positive electrode and silicon-carbon as the negative electrode, a 5Ah soft-pack battery is assembled.

[0096] Liquid injection and formation: Liquid injection, impregnation, and sealing are carried out according to conventional processes, and formation is performed with a current of 0.05C.

[0097] Gelation: Place the battery in a 75°C oven and let it stand for 6 hours.

[0098] Performance: The electrolyte inside the battery is in a uniform gel state. After 500 cycles at 1C rate at room temperature, the capacity retention rate is 92%; the needle penetration test was passed without fire or explosion.

[0099] Example 2: The difference from Example 1 is that the PEO content is increased to 15 wt%. The viscosity of the gel electrolyte composition is >500 mPa·s, making injection difficult, resulting in incomplete wetting, high internal resistance of the battery, and only 85% of the capacity is utilized.

[0100] Example 3 The difference from Example 1 is that methyl methacrylate is replaced with ethyl acrylate.

[0101] Example 4 The difference from Example 1 is that the PEO content is 8 wt%.

[0102] Example 5 The difference from Example 1 is that the PEO content is 10 wt%.

[0103] Example 6 The difference from Example 1 is that the PEO content is 1 wt%.

[0104] Example 7 The difference from Example 1 is that the Mw of PEO is 100k.

[0105] Example 8 The difference from Example 1 is that the Mw of PEO is 300k.

[0106] Example 9 The difference from Example 1 is that KH570 is replaced with vinyltrimethoxysilane (VTMS).

[0107] Example 10 The difference from Example 1 is that the amount of AIBN used is 0.1 wt%.

[0108] Example 11 The difference from Example 1 is that the amount of AIBN used is 1 wt%.

[0109] Example 12 The difference from Example 1 is that the amount of AIBN used is 1.5 wt%.

[0110] Example 13 The difference from Example 1 is that it is formed with a current of 0.1C.

[0111] Example 14 The difference from Example 1 is that no formation step is performed.

[0112] Comparative Example 1: (Physically Mixed Inorganic Phases) The difference from Example 1 is that an equal amount of nano-SiO2 powder was used instead of KH570. SiO2 is prone to agglomeration, resulting in uneven gelation and poor battery cycle performance (78% retention rate after 500 cycles).

[0113] Comparative Example 2: (Liquid Electrolyte) The difference from Example 1 is that a common electrolyte without monomers and initiators was used, and the battery performance was good at first but burned violently when punctured.

[0114] Comparative Example 3 The difference from Example 1 is that KH570 is replaced with (3-chloropropyl)trimethoxysilane.

[0115] Comparative Example 4 The difference from Example 1 is that KH570 is replaced with trimethoxysilane.

[0116] In the above examples and comparative examples, the viscosity was tested at 25°C.

[0117] Electrochemical performance testing: The electrochemical performance of the above examples and comparative examples was tested. After cycling 500 times at a 1C rate in the range of 2.75V-4.2V at room temperature, the capacity retention of each example and comparative example was tested.

[0118] Needle prick test: The above embodiments and comparative examples were subjected to needle penetration tests, which can be performed with reference to the needle penetration method for battery safety regulations in Japanese JIS certification.

[0119] The electrochemical and needle puncture test results of the above embodiments and comparative examples are shown in Table 1.

[0120] Table 1

[0121] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A gel electrolyte composition comprising an acrylate monomer, polyethylene oxide, a bifunctional alkoxysilane crosslinking agent, an initiator, a lithium salt, and a solvent, wherein, The bifunctional alkoxysilane crosslinking agent is an alkoxysilane with terminal unsaturated bonds.

2. The gel electrolyte composition according to claim 1, characterized in that, The bifunctional alkoxysilane crosslinking agent has the structure shown in Formula 1: Formula 1 Among them, R1, R2, and R3 may be the same or different, and each is independently selected from H, substituted or unsubstituted C1-C20 alkyl groups; R4, R5, and R6 may be the same or different, and each is independently selected from H, halogen, cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C1-C30 heteroaryl; The substituents are selected from any one or a combination of at least two of the following: deuterium, halogen, cyano, nitro, C1-C20 alkyl, C1-C20 alkoxy, C3-C20 cycloalkyl, C6-C30 aryl, and C3-C30 heteroaryl. n is an integer from 1 to 10, preferably an integer from 1 to 5; Preferably, R1, R2, and R3 are the same and each is independently selected from H, substituted or unsubstituted C1-C5 alkyl groups; and / or R4, R5, and R6 may be the same or different, and each is independently selected from H, halogen, cyano, nitro, amino, acyl, carbonyl, carboxylic acid, ester, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, substituted or unsubstituted C1-C5 alkyl; and / or The substituents are selected from deuterium, halogen, cyano, nitro, and C1-C5 alkyl groups; Preferably, the bifunctional alkoxysilane crosslinking agent is selected from γ-(methacryloyloxy)propyltrimethoxysilane; and / or The acrylate monomers are selected from methyl methacrylate and / or ethyl acrylate; and / or The initiator is selected from thermal initiators, preferably from azobisisobutyronitrile and / or benzoyl peroxide, and / or The lithium salt is selected from lithium bis(trifluoromethanesulfonylimide) and / or lithium hexafluorophosphate; and / or The solvent is selected from organic solvents, preferably carbonate solvents, and more preferably one or more selected from ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and / or The weight-average molecular weight of the polyoxyethylene is 10,000 to 300,000.

3. The gel electrolyte composition according to claim 1 or 2, characterized in that, Based on the total weight of the gel electrolyte composition (100%), the content of the acrylate monomer is 5 wt% to 25 wt%, the content of the polyethylene oxide is 1 wt% to 8 wt%, the content of the bifunctional alkoxysilane crosslinking agent is 0.5 wt% to 25 wt%, the content of the initiator is 0.1 wt% to 1.5 wt%, the content of the lithium salt is 8 wt% to 35%, and the balance is the solvent.

4. The gel electrolyte composition according to any one of claims 1-3, characterized in that, The viscosity of the gel electrolyte composition at 25°C is less than 20 mPa·s.

5. A gel electrolyte, formed by reacting the gel electrolyte composition according to any one of claims 1-4; Preferably, the method for preparing the gel electrolyte includes: The gel electrolyte composition is obtained by injecting it into the battery and reacting it.

6. A secondary battery comprising the gel electrolyte of claim 5, preferably, the secondary battery being a lithium battery.

7. A method for preparing a secondary battery, comprising: (1) Install the battery cell containing the positive electrode, separator and negative electrode into the battery casing; (2) Inject the gel electrolyte composition of any one of claims 1-4 into the battery casing to wet the positive electrode, negative electrode and separator, and then precharge to obtain the formed battery; (3) React the formed battery to obtain the secondary battery; Preferably, the reaction temperature is 60~85℃, and / or The reaction time is 2 to 10 hours.

8. A battery module comprising the secondary battery of claim 6 or the secondary battery prepared by the preparation method of claim 7.

9. A battery pack comprising the battery module of claim 8.

10. An electrical device comprising the secondary battery of claim 6 or the secondary battery prepared by the preparation method of claim 7, wherein the secondary battery is used as a power source for the electrical device; Preferably, the electrical device includes one or more of the following: electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, electric bicycle, electric scooter, electric truck, and electric boat.

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