Silicon-containing compound, electrolyte solution for secondary battery, secondary battery, and electric device

Abstract

The invention provides a silicon-containing compound, an electrolyte for a secondary battery, the secondary battery and an electric device. The general formula of the silicon-containing compound is shown as a formula I. In the formula I, X1 and X2 independently comprise-NR4 <-> or-O <->; r3 comprises hydrogen, halogen, carbonyl, carboxyl, ester group, cyano group, ether alkyl, halogen substituted or unsubstituted C1-C10 alkyl, halogen substituted or unsubstituted C6-C60 aryl, halogen substituted or unsubstituted cyclic sulfonate group, halogen substituted or unsubstituted cyclic sulfate group, halogen substituted or unsubstituted cyclic sulfite group, and halogen substituted or unsubstituted cyclic sulfonyl, and R3 comprises hydrogen, halogen, carbonyl, carboxyl, ester group, cyano group, ether alkyl, halogen substituted or unsubstituted C1-C10 alkyl, halogen substituted or unsubstituted C6-C60 aryl, halogen substituted or unsubstituted cyclic sulfonate group, halogen substituted or unsubstituted cyclic sulfate group, and halogen substituted or unsubstituted cyclic sulfonyl. A halogen-substituted or unsubstituted cyclic carbonate group; r1, R2, R4 and R51 respectively and independently comprise hydrogen, halogen substituted or unsubstituted C1-C10 saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C60 aryl, carbonyl, carboxyl, ester group, cyano or ether alkyl.

Description

Silicon-containing compound, electrolyte for secondary battery, secondary battery and electrical device Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a silicon-containing compound, an electrolyte for a secondary battery, a secondary battery, and an electrical device. Background Art

[0002] In recent years, secondary batteries have been widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. With the widespread use of secondary batteries, higher requirements have been placed on their energy density and cycle performance.

[0003] The electrolyte is the carrier for ion transport in secondary batteries, conducting ions between the positive and negative electrodes. However, during the charge and discharge process of secondary batteries, the electrolyte easily decomposes to produce byproducts, which can significantly degrade battery performance and even cause safety issues.

[0004] Summary of the Invention

[0005] This application is based on the above-mentioned issues and aims to provide a silicon-containing compound, a secondary battery electrolyte, a secondary battery, and an electrical device. When the silicon-containing compound of this application is used in the electrolyte of a secondary battery, it can remove byproducts in the electrolyte, form a stable interface coating on the electrode surface, improve interface stability, reduce battery internal resistance, and improve the battery's high-temperature cycling performance and high-temperature storage performance.

[0006] The first aspect of the present application provides a silicon-containing compound, the general formula of which is shown in Formula I:

[0007] Among them, X1 and X2 each independently include

[0008] R3 includes hydrogen, halogen, carbonyl, carboxyl, ester, cyano, ether, halogen-substituted or unsubstituted C1-C 10 Alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a halogen-substituted or unsubstituted cyclic sulfonate group, a halogen-substituted or unsubstituted cyclic sulfate group, a halogen-substituted or unsubstituted cyclic sulfite group, a halogen-substituted or unsubstituted cyclic sulfone group, and a halogen-substituted or unsubstituted cyclic carbonate group;

[0009] R1, R2, R4, R5 1 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group, or an ether alkyl group;

[0010] n1 is any integer from 1 to 6, and can be 1 or 2.

[0011] The structure of the silicon-containing compound of the present application contains -N-Si-O-, -N-Si-N- or -O-Si-O- bonds and cyclic ester structures connected thereto. Si-N bonds and Si-O bonds react easily with byproducts such as moisture or hydrogen fluoride present in the battery, causing the chemical bonds to break, effectively removing moisture or hydrogen fluoride from the battery, reducing the performance degradation caused by moisture or hydrogen fluoride, and improving the safety of the battery. In addition, the cyclic ester structure in the silicon-containing compound can be reduced and decomposed and ring-opening polymerized on the surface of the active material to form an interface coating layer, thereby protecting the electrode active material from being consumed by components in the electrolyte, improving interfacial stability, reducing interfacial impedance, and improving cycle stability. The silicon-containing compound provided in the present application can effectively improve the cycle stability and storage stability of the battery and reduce the internal resistance of the battery.

[0012] In any embodiment, R3 includes at least one of the following groups:

[0013] Among them, R5 2 、R5 3 、R5 4 、R5 5 、R5 6 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group, or an ether alkyl group;

[0014] n2 is any integer from 1 to 6, and can be 1 or 2.

[0015] In this bicyclic ester structure connected by -N-Si-O-, -N-Si-N- or -O-Si-O- bonds, compared with the monocyclic ester structure, it can more efficiently improve battery performance, reduce battery internal resistance, and increase battery cycle capacity retention and storage capacity retention.

[0016] In any embodiment, the compound represented by Formula I includes at least one of Compound A11 to Compound A20:

[0017] A second aspect of the present application provides an electrolyte for a secondary battery, wherein the electrolyte includes the silicon-containing compound of the first aspect.

[0018] In any embodiment, in the electrolyte, based on the total mass of the electrolyte, the mass content of the silicon-containing compound is less than or equal to 30%, and can be optionally 0.3%-10%.

[0019] When the mass content of the silicon compound in the electrolyte is within an appropriate range, the interface stability can be improved, the internal resistance of the battery can be reduced, and the high-temperature cycle performance and storage stability of the battery can be improved.

[0020] In any embodiment, the electrolyte further comprises a fluorinated cyclic carbonate.

[0021] Fluorinated cyclic carbonates can form a synergistic effect with silicon-containing compounds to further improve interface stability, reduce battery internal resistance, and enhance the battery's high-temperature cycle performance and high-temperature storage performance.

[0022] In any embodiment, the fluorinated cyclic carbonate includes one or more of fluoroethylene carbonate, difluoroethylene carbonate, trifluoropropylene carbonate, 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3-dioxolane-2-one, and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolane-2-one.

[0023] The aforementioned fluorinated cyclic carbonates can form an effective SEI film on the electrode surface, increasing the rate of ion migration in the electrolyte and significantly improving the battery's charge-discharge performance at high rates. For silicon-based negative electrode active materials, fluorinated ethylene carbonate forms a thin, tough, and self-healing SEI film. This can inhibit the structural breakage of silicon-based materials caused by volume expansion during charge and discharge, reducing irreversible capacity loss and extending the battery's lifespan.

[0024] In any embodiment, based on the total mass of the electrolyte, the mass content of the fluorinated cyclic carbonate is 2%-20%, optionally 5%-15%.

[0025] When the mass content of the fluorinated cyclic carbonate is 2%-20%, the fluorinated cyclic carbonate can form a stable SEI film at the interface between the negative electrode and the electrolyte, and at the same time, the gas production problem will not be aggravated due to excessively high content.

[0026] In any embodiment, the electrolyte further includes one or more of chain esters, fluorine-free cyclic esters, and ethers, which can be selected from diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, tetrahydrofuran, dimethyl ether, diethyl ether, and one or more of ethylene glycol dimethyl ether.

[0027] A third aspect of the present application provides a secondary battery, comprising the silicon-containing compound of the first aspect or the electrolyte for a secondary battery of the second aspect.

[0028] In any embodiment, the secondary battery includes a negative electrode active material, and the negative electrode active material includes a silicon-based material; optionally, the silicon-based material includes one or more of elemental silicon, silicon-oxygen material, and silicon-carbon material.

[0029] Silicon-based negative electrodes have a theoretical gram capacity significantly higher than that of graphite negative electrodes. However, due to the huge volume changes during the cycle of silicon-based negative electrode materials, particles are easily broken and pulverized, which in turn causes the SEI film to break and regenerate, resulting in a large irreversible capacity loss, which greatly reduces the cycle life of the battery. The silicon-containing compound of the present application is particularly suitable for silicon-based negative electrode materials. It can effectively reduce the water or hydrofluoric acid produced in the electrolyte, reduce the impedance deterioration of the battery during the cycle by generating an interface coating layer, and improve the interface stability. At the same time, it can synergize with fluoroethylene carbonate to improve the repair ability of the silicon-based material interface coating layer while reducing the gas production of fluorocarbonate at high temperatures, thereby improving the cycle performance and storage performance of the battery at high temperatures.

[0030] In any embodiment, based on the total mass of the negative electrode active material, the mass content of the silicon-based material is greater than or equal to 10%, and more preferably 20%-50%.

[0031] When the mass content of silicon-based materials is greater than or equal to 10% based on the total mass of the negative electrode active material, the battery capacity and energy density can be significantly improved. However, high content of silicon-based materials causes excessive volume changes during cycling, resulting in a significant decrease in cycling performance. The addition of silicon-containing compounds to the electrolyte can effectively reduce the battery's internal resistance and improve its cycling and storage performance.

[0032] A fourth aspect of the present application provides an electrical device comprising the secondary battery of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0034] FIG2 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG1 ;

[0035] FIG3 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0036] Reference numerals:

[0037] 1 secondary battery; 11 housing; 12 electrode assembly; 13 cover plate. DETAILED DESCRIPTION

[0038] Below, the embodiments of the binder, preparation method, electrode, battery, and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0039] " range " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0042] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0043] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0044] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0045] The electrolyte in the prior art mainly uses lithium hexafluorophosphate as lithium salt. During the circulation and storage process, lithium hexafluorophosphate easily produces water and hydrogen fluoride. Water easily reacts violently with metal materials, causing battery safety problems; while hydrogen fluoride catalyzes the decomposition of the electrolyte, destroying the interface structure between the electrolyte and the active material, and also causes the dissolution of transition metal ions in the positive electrode active material, destroying the lattice structure and deteriorating the performance of the battery cell. In the prior art, additives are often added to the electrolyte to form an interface coating layer at the interface of the electrolyte active material by an in-situ coating method to improve the interface stability. However, the interface coating layer formed in the current prior art generates a single interface component, which cannot effectively protect the electrode active material during long-term charge and discharge cycles, and the effect on improving the battery cell performance is not ideal; and it produces serious gas at high temperatures, making it difficult to effectively improve the high-temperature performance of the battery.

[0046] [Silicon-containing compounds]

[0047] Based on this, the present application provides a silicon-containing compound, the general formula of the silicon-containing compound is as shown in Formula I,

[0048] Among them, X1 and X2 each independently include

[0049] R3 includes hydrogen, halogen, carbonyl, carboxyl, ester, cyano, ether alkyl, halogen substituted or unsubstituted C1-C 10 Hydrocarbon, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a halogen-substituted or unsubstituted cyclic sulfonate group, a halogen-substituted or unsubstituted cyclic sulfate group, a halogen-substituted or unsubstituted cyclic sulfite group, a halogen-substituted or unsubstituted cyclic sulfone group, and a halogen-substituted or unsubstituted cyclic carbonate group;

[0050] R1, R2, R4, R5 1 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated hydrocarbon, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group, or an ether alkyl group;

[0051] n1 is any integer from 1 to 6, and can be 1 or 2.

[0052] As used herein, "carbonyl" refers to

[0053] In this context, "carboxyl" refers to

[0054] In this context, "ester group" refers to

[0055] In this article, "cyano" refers to

[0056] In this context, "ether alkyl" refers to a C n H 2n+1 -O-.

[0057] In this article, “C1-C 10 "Hydrocarbyl" refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, optionally with unsaturation, having from one to ten carbon atoms, and attached to the rest of the molecule by a single bond.

[0058] In this article, the term "C6-C 60 "Aryl" refers to a monovalent group of a carbocyclic aromatic system having 6 to 60 carbon atoms.

[0059] As used herein, the term "substituted" refers to a compound or chemical moiety in which at least one hydrogen atom is replaced by another chemical moiety, wherein the substituents independently include: hydroxyl, thiol, amino, cyano, nitro, aldehyde, halogen, alkenyl, alkynyl, aryl, heteroaryl, C 1- C6 alkyl, C 1- C6 alkoxy.

[0060] Herein, "halogen-substituted" means that at least one hydrogen atom in the group is replaced by a halogen atom, and the halogen atom includes at least one of F, Cl, Br, and I. In some embodiments, halogen-substituted means fluorine-substituted.

[0061] In this context, the term "halogen-substituted C1-C 10 "Saturated or unsaturated hydrocarbon group" refers to a C1-C2 group in which at least one hydrogen atom is replaced by a halogen atom. 10 Hydrocarbon, C1-C 10 Unsaturated bonds may optionally be present in the hydrocarbon group.

[0062] In some embodiments, n1 is 1 or 2. In this case, the cyclic ester structure is a five-membered ring or a six-membered ring. In this case, the ring structure is highly active, and the silicon-containing compound easily undergoes a ring-opening reaction to form an interface coating layer on the surface of the electrode active material.

[0063] In this context, the term "halogen-substituted C6-C 60 "Aryl" refers to a C6-C 60 Aryl.

[0064] In this context, a cyclic sulfonate group refers to a heterocyclic group containing a sulfonate group, wherein the carbon of the heterocyclic ring is connected to X2 in Formula I, including but not limited to

[0065] In this context, a cyclic sulfate group refers to a heterocyclic group containing a sulfate group, wherein the carbon of the heterocyclic ring is connected to X2 in Formula I, including but not limited to

[0066] In this context, a cyclic sulfite group refers to a heterocyclic group containing a sulfite group, wherein the carbon of the heterocyclic ring is connected to X2 in Formula I, including but not limited to

[0067] In this context, a cyclic sulfone group refers to a heterocyclic group containing a sulfone group, wherein the carbon of the heterocyclic ring is connected to X2 in Formula I, including but not limited to

[0068] In this context, a cyclic carbonate group refers to a heterocyclic group containing a carbonate group, wherein the carbon of the heterocyclic ring is connected to X2 in Formula I, including but not limited to The structure of the silicon-containing compound of the present application contains -N-Si-O-, -N-Si-N- or -O-Si-O- bonds and sulfate groups. Heterocycle. The Si-N bond and Si-O bond easily react with the moisture and hydrogen fluoride present in the battery and break, thereby effectively removing the moisture and hydrogen fluoride in the battery and improving the cycle performance and safety performance of the battery. The sulfate ester group in the silicon-containing compound is easily reduced and decomposed during the charge and discharge process of the battery to form an interface coating layer including sulfates, sulfites, sulfur-containing organic small molecules and sulfur-containing polymers. The interface coating of sulfates and sulfites can improve the ion conduction properties of the electrode interface and reduce the interface impedance. The coating of sulfur-containing organic matter can slow down the volume effect of the electrode active material during ion insertion and extraction, which is beneficial to improve the interface stability and the cycle stability of the battery, especially the cycle stability at high temperature.

[0069] In some embodiments, R3 comprises at least one of the following groups:

[0070] One or more of

[0071] Among them, R5 2 、R5 3 、R5 4 、R5 5 、R5 6 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group, or an ether alkyl group;

[0072] n2 is any integer from 1 to 6, and can be 1 or 2.

[0073] The above-mentioned silicon-containing compound contains a bicyclic ester structure connected by -N-Si-O-, -N-Si-N- or -O-Si-O- bonds. In this bicyclic ester structure connected by -N-Si-O-, -N-Si-N- or -O-Si-O- bonds, compared with the monocyclic ester structure, it can more efficiently improve battery performance, reduce battery internal resistance, and improve the battery's high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate.

[0074] In some embodiments, R1, R2, R4, R5 1 Each independently includes at least one of hydrogen, halogen-substituted or unsubstituted C1-C3 alkyl.

[0075] In some embodiments, R1, R2, R4, R5 1 Each independently includes hydrogen, F substituted or unsubstituted C1-C3 alkyl.

[0076] In some embodiments, the compound represented by Formula I includes at least one of Compound A11 to Compound A20:

[0077] In some embodiments, a silicon-containing compound is added to the electrolyte in a small amount as an additive.

[0078] In some embodiments, a silicon-containing compound is added to the electrolyte in a large amount as a solvent.

[0079] [Synthesis Method of Silicon-Containing Compounds]

[0080] Those skilled in the art can synthesize the silicon-containing compounds of the present application using known methods, or can synthesize the silicon-containing compounds according to the embodiments of the present disclosure using the methods described below using alkylation reactions of halogenated hydrocarbons and alkylation reactions of amino groups. However, the synthesis methods of the silicon-containing compounds according to the embodiments of the present disclosure are not limited thereto.

[0081] In some embodiments, a cyclic ester monomer containing a halogen substituent and a monomer represented by formula II containing a hydroxyl group are subjected to an alkylation reaction with a halogenated hydrocarbon in the presence of NaOH, so that the halogen of the cyclic ester monomer reacts with the hydroxyl group of the monomer represented by formula II to prepare a silicon-containing compound or an intermediate thereof.

[0082] Wherein, R6 and R7 are independently hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C 60 At least one of aryl, carbonyl, carboxyl, ester, cyano or ether alkyl; X3 and X4 each independently include at least one of -NH3, -OH, -OR8, -NH2R9, R8 and R9 each independently include halogen, carbonyl, carboxyl, ester, cyano, ether alkyl, halogen substituted or unsubstituted C1-C 10 Alkyl, halogen substituted or unsubstituted C6-C 60 At least one of the aromatic groups.

[0083] In some embodiments, a cyclic ester monomer containing a halogen substituent and a monomer represented by Formula II containing an amino group are subjected to an alkylation reaction of the amino group in an acidic environment, so that the halogen of the cyclic ester monomer reacts with the amino group of the monomer represented by Formula II to prepare a silicon-containing compound or an intermediate thereof.

[0084] In some embodiments, a cyclic ester monomer containing a halogen substituent and a monomer represented by formula II containing a hydroxyl group are subjected to an alkylation reaction with a halogenated hydrocarbon in the presence of NaOH, and then the product is subjected to an amino group alkylation reaction with a monomer represented by formula II containing an amino group in an acidic environment to prepare a silicon-containing compound.

[0085] In some embodiments, the silicon-containing compound A11 can be synthesized by the method described below.

[0086] Will and NaOH is mixed in a solvent, and the molar ratio of the three raw materials is 1:1:(1-2) in sequence; after heating and reacting for 6-24 hours, the product is purified. The above product and The mixture is mixed in a solvent at a molar ratio of 1:1, and the reaction is continued for 4-12 hours in an acidic environment with a pH value of 3-6 to obtain compound A11.

[0087] The reaction process is as follows:

[0088] In some embodiments, the solvent may be selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or acetone.

[0089] Compounds A12 to A20 can be synthesized by referring to the synthesis method of Reference A11. The difference is that the monomers added during the preparation process are changed according to the target product. [Electrolyte for Secondary Batteries]

[0090] In one embodiment of the present application, an electrolyte for a secondary battery is provided, comprising the silicon-containing compound according to any embodiment.

[0091] In some embodiments, in the electrolyte, based on the total mass of the electrolyte, the mass content of the silicon-containing compound is less than or equal to 30%, and can be optionally 0.3%-10%.

[0092] In some embodiments, in the electrolyte, the mass content of the silicon-containing compound, based on the total mass of the electrolyte, may be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%.

[0093] When the mass content of silicon compounds in the electrolyte is within an appropriate range, the interface stability can be improved, the internal resistance of the battery can be reduced, and the cycle performance and storage stability of the battery can be improved, especially the performance at high temperatures.

[0094] In some embodiments, the silicon-containing compound can be used as a solvent in the electrolyte. When the silicon-containing compound is used as a solvent in the electrolyte, it can form an interface coating layer on the electrode surface, reducing direct contact between the electrolyte and the electrode active material, improving the interface stability, and reducing the internal resistance of the battery.

[0095] In some embodiments, silicon-containing compounds can be used as additives in electrolytes. When used as additives in electrolytes, silicon-containing compounds can synergize with solvents or other additives in the electrolyte to further optimize the SEI film, reduce battery internal resistance, and improve battery cycle performance and storage performance, especially performance at high temperatures.

[0096] In some embodiments, the electrolyte may further include a fluorinated cyclic carbonate.

[0097] Due to their weak resistance to reduction, fluorinated cyclic carbonates undergo reduction and decomposition on the negative electrode surface before other solvents, helping to form a stable interfacial film on the negative electrode surface and improving the battery's cycling stability. Furthermore, when used as an additive with silicon-containing compounds, fluorinated cyclic carbonates can further reduce battery internal resistance, improve interfacial stability, and enhance the battery's cycling and storage performance.

[0098] In some embodiments, the fluorinated cyclic carbonate may include one or more of fluoroethylene carbonate, difluoroethylene carbonate, trifluoropropylene carbonate, 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3-dioxolane-2-one, and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolane-2-one.

[0099] These fluorinated cyclic carbonates can form an effective SEI film on the electrode surface, increasing the rate of ion migration in the electrolyte and improving the battery's charge-discharge performance at high rates. For silicon-carbon anode active materials, fluorinated ethylene carbonate, due to its thin, tough, and self-healing SEI film, can suppress the structural breakage of silicon-based materials caused by volume expansion during charge and discharge, thereby extending the lifespan of the silicon-based material.

[0100] In some embodiments, based on the total mass of the electrolyte, the mass content of the fluorinated cyclic carbonate is 2%-20%, optionally 5%-15%.

[0101] In some embodiments, the mass content of the fluorinated cyclic carbonate may be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20% based on the total mass of the electrolyte.

[0102] When the mass content of the fluorinated cyclic carbonate is 2%-20%, the fluorinated cyclic carbonate can form a stable SEI film at the interface between the negative electrode and the electrolyte, and at the same time, the gas production problem will not be aggravated due to excessively high content.

[0103] In some embodiments, the electrolyte further comprises one or more of a chain ester, a fluorine-free cyclic ester, and an ether, and may be selected from diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, tetrahydrofuran, dimethyl ether, diethyl ether, and ethylene glycol dimethyl ether. In some embodiments, the electrolyte comprises ethylene carbonate and ethyl methyl carbonate.

[0104] In some embodiments, the electrolyte further comprises an electrolyte salt. The electrolyte salt may comprise LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), one or more of LiPF6, LiBF4, LiBOB, LiAsF6, Li(FSO2)2N, LiCF3SO3, and LiClO4, wherein x and y are natural numbers.

[0105] [Positive electrode]

[0106] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.

[0107] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0108] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0109] In some embodiments, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0110] In some embodiments, the positive electrode active material is a nickel-rich material, and the molar ratio of nickel in the transition metal of the positive electrode active material is higher than 85%.

[0111] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0112] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0113] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0114] [Negative electrode]

[0115] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0116] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0117] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0118] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: lithium metal and its alloys, artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate, etc. The silicon-based material may include at least one of elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen materials and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0119] In some embodiments, the negative electrode film layer may further include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0120] In some embodiments, the negative electrode film layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0121] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0122] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0123] [Isolation film]

[0124] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0125] In some embodiments, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0126] [Secondary battery]

[0127] In one embodiment of the present application, a secondary battery is provided, comprising the electrolyte according to any embodiment.

[0128] In some embodiments, the secondary battery is a lithium ion secondary battery or a sodium ion secondary battery.

[0129] In some embodiments, the secondary battery includes a negative electrode active material, wherein the negative electrode active material includes a silicon-based material. Optionally, the silicon-based material includes one or more of elemental silicon, silicon-oxygen material, and silicon-carbon material.

[0130] Silicon-based negative electrodes have a theoretical gram capacity significantly higher than that of graphite negative electrodes. However, due to the huge volume changes during the cycle of silicon-based negative electrode materials, particles are easily broken and pulverized, which in turn causes the SEI film to break and regenerate, resulting in a large irreversible capacity loss, which greatly reduces the cycle life of the battery. The silicon-containing compound of the present application is particularly suitable for silicon-based negative electrode active materials. It can effectively reduce the water or hydrofluoric acid produced in the electrolyte, reduce the impedance deterioration of the battery during the cycle by generating an interface coating layer, and improve the interface stability. At the same time, it can synergize with fluoroethylene carbonate to improve the repair ability of the silicon-based material interface coating layer while reducing the gas production of fluorocarbonate at high temperatures, thereby improving the cycle performance and storage performance of the battery at high temperatures.

[0131] In some embodiments, based on the total mass of the negative electrode active material, the mass content of the silicon-based material is greater than or equal to 10%, and may be 20%-50%.

[0132] In some embodiments, the mass content of the silicon-based material may be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% based on the total mass of the negative electrode active material.

[0133] When the mass content of silicon-based materials is greater than or equal to 10% based on the total mass of the negative electrode active material, the battery capacity and energy density can be significantly improved. However, high content of silicon-based materials causes excessive volume changes during cycling, resulting in a significant decrease in cycling performance. The addition of silicon-containing compounds to the electrolyte can effectively reduce the battery's internal resistance and improve its cycling and storage performance.

[0134] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0135] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0136] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. For example, FIG1 shows a secondary battery 1 with a square structure as an example.

[0137] In some embodiments, referring to Figure 2, the outer packaging may include a shell 11 and a cover plate 13. The shell 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 12 through a winding process or a lamination process. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 12. The number of electrode assemblies 12 contained in the secondary battery 1 can be one or more, and those skilled in the art can select according to specific actual needs.

[0138] In addition, the present application also provides an electrical device, which includes the secondary battery provided in the present application. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can include, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0139] As an electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0140] FIG3 shows an example of an electric device, which may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0141] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0142] Example

[0143] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0144] 1. Preparation method

[0145] Example 1

[0146] (1) Preparation of positive electrode sheet

[0147] Positive electrode: the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) are dissolved in solvent N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5, and are fully stirred and mixed to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0148] (2) Preparation of negative electrode sheet

[0149] Negative electrode: The negative electrode active material (the mass ratio of silicon oxide to graphite is 3:7), the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a weight ratio of 90:4:4:2, and are evenly mixed to prepare a negative electrode slurry; then the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode film is obtained after drying, and then the negative electrode sheet is obtained by cold pressing and slitting.

[0150] (3) Preparation of electrolyte

[0151] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7, 12.5% ​​by mass of LiPF6 lithium salt was added and dissolved in the organic solvent, and then 1% by mass of compound A11 was added as an additive and stirred uniformly to obtain an electrolyte.

[0152] (4) Isolation membrane

[0153] Polypropylene film is used as the isolation film.

[0154] (5) Preparation of batteries

[0155] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrodes to provide insulation. The electrode assembly is then wound to form an electrode assembly. The electrode assembly is placed in a battery casing, dried, and then injected with the electrolyte. The lithium-ion battery is then manufactured through formation and resting processes.

[0156] Example 2-10

[0157] In Examples 2-10, Compound A12, Compound A13, Compound A14, Compound A15, Compound A16, Compound A17, Compound A18, Compound A19, and Compound A20 are respectively used as additives in the electrolyte, and the other steps are basically the same as in Example 1.

[0158] Examples 11-18

[0159] In Examples 11-18, the mass content of the additive compound A12 in the electrolyte was adjusted, and the other steps were basically the same as in Example 2.

[0160] Example 19

[0161] In Example 19, the preparation method of the electrolyte was adjusted, and the other steps were basically the same as those in Example 2.

[0162] The preparation method of the electrolyte in Example 19 is as follows: in an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) are mixed in a volume ratio of 2:7:1, 12.5% ​​by mass of LiPF6 lithium salt is added and dissolved in the organic solvent, and then 1% by mass of compound A11 is added as an additive, stirred evenly, and the electrolyte of Example 19 is obtained.

[0163] Comparative Example 1

[0164] No electrolyte additive was added to the electrolyte of Comparative Example 1, and other steps were basically the same as those of Example 1.

[0165] Comparative Examples 2-3

[0166] In Comparative Examples 2-3, vinyl sulfate and 1,3-propane sultone were used as additives in the electrolyte, respectively, and the other steps were basically the same as those in Example 1.

[0167] See Table 1 for specific parameters.

[0168] 2. Battery performance test

[0169] 1. Capacity retention after 1000 cycles at 45°C

[0170] At 45°C, the lithium-ion batteries prepared in each embodiment and comparative example were charged to 4.3V at a constant current of 1C, then charged at a constant voltage of 4.3V until the current was less than 0.05C, and then the lithium-ion batteries were discharged to 3.0V at a constant current of 1C. This is one charge and discharge process, and the discharge capacity at this time is recorded as the discharge capacity of the battery in the first cycle. Repeat the charging and discharging in this way, record the discharge capacity of the battery after the 1000th cycle, and calculate the capacity retention rate of the lithium-ion battery after 1000 cycles. The capacity retention rate (%) of the battery after 1000 cycles at 45°C = (discharge capacity after the 1000th cycle / discharge capacity of the first cycle) × 100%.

[0171] 2. Battery internal resistance growth rate

[0172] At 25°C, the lithium-ion batteries prepared in each example and comparative example, as well as the lithium-ion batteries cycled 1000 times at 45°C, were charged at a constant current of 1C to 4.3V, then charged at a constant voltage of 4.3V until the current was less than 0.05C, and then discharged at 1C for 30 minutes, adjusting the battery capacity to 50% SOC. The positive and negative test leads of a TH2523A AC internal resistance tester were then placed in contact with the positive and negative terminals of the battery, respectively. The internal resistance of the battery was read using the internal resistance tester and recorded as the initial battery internal resistance R1 (mΩ) and the battery internal resistance after 1000 cycles R2 (mΩ), respectively. The battery internal resistance growth rate = (R2 - R1) / R1 × 100%.

[0173] 3. Capacity retention after storage at 60°C for 100 days

[0174] At 25°C, the lithium-ion batteries prepared in each embodiment and comparative example were charged at a constant current of 1C to a voltage of 4.3V, then charged at a constant voltage of 4.3V to a current of 0.05C, and then the lithium-ion batteries were discharged at a constant current of 1C to 3.0V. This is one charge and discharge process. The fully charged lithium-ion battery was then placed in a 60°C constant temperature box and the capacity after 100 days of storage was tested. The capacity retention rate (%) after 100 days of storage at 60°C = (discharge capacity after 100 days of storage / discharge capacity of the first cycle) × 100%.

[0175] 3. Test Results

[0176] The test results of the above embodiments and comparative examples are shown in Table 1.

[0177] Table 1

[0178] It can be seen from Table 1 that the electrolytes of Examples 1-19 all contain the silicon-containing compound shown in Formula I. Compared with the batteries prepared using electrolytes not containing silicon-containing compounds in Comparative Examples 1-3, the batteries of Examples 1-19 all exhibit lower internal resistance growth rate, better high-temperature cycle performance and high-temperature storage performance.

[0179] Comparison of Examples 1-10 with Comparative Example 1 shows that, compared to an electrolyte without a silicon-containing compound, the addition of a silicon-containing compound significantly reduces the internal resistance growth rate of the battery and improves the battery's high-temperature cycling and storage performance. Specifically, compared to the battery in Comparative Example 1, the capacity retention of the batteries in Examples 1-10 after 1000 cycles increased by approximately 1.5 to 2.5 times, and the capacity retention after 300 days of storage at 60°C increased by approximately 3 to 4 times.

[0180] From the comparison of Examples 11-18 and Comparative Example 1, it can be seen that compared with the electrolyte not containing the silicon-containing compound, when the mass content of the silicon-containing compound is 0.1%-35% based on the total mass of the electrolyte, the battery cycle internal resistance growth rate is reduced and the cycle capacity retention rate is improved.

[0181] From the comparison of Examples 11-18 and Comparative Example 1, it can be seen that compared with the electrolyte not containing the silicon-containing compound, when the mass content of the silicon-containing compound is 0.3%-10% based on the total mass of the electrolyte, the cycle capacity retention rate and high-temperature storage capacity retention rate of the battery are improved more significantly.

[0182] From the comparison between Examples 1-19 and Comparative Examples 2-3, it can be seen that compared with the electrolyte containing vinyl sulfate or 1,3-propane sultone as an additive, the electrolyte containing silicon compounds A11 to A20 as additives can more significantly reduce the internal resistance growth rate during the cycle process and improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0183] From the comparison between Examples 1-8 and Examples 9-10, it can be seen that the silicon-containing compound containing a bicyclic ester structure can more significantly reduce the internal resistance growth rate of the electrolyte and improve the cycle performance and storage performance of the battery at high temperature compared to the silicon-containing compound containing a monocyclic ester structure.

[0184] From the comparison between Example 2 and Example 19, it can be seen that when the electrolyte contains EC, EMC and the silicon-containing compound A12 is used as an additive, the addition of fluoroethylene carbonate (FEC) can cooperate synergistically with the silicon-containing compound A12 to further reduce the internal resistance growth rate of the battery and improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0185] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A silicon-containing compound, characterized in that Its general formula is shown in Formula I, Among them, X1 and X2 each independently include R3 includes hydrogen, halogen, carbonyl, carboxyl, ester, cyano, ether, halogen-substituted or unsubstituted C1-C 10 Alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a halogen-substituted or unsubstituted cyclic sulfonate group, a halogen-substituted or unsubstituted cyclic sulfate group, a halogen-substituted or unsubstituted cyclic sulfite group, a halogen-substituted or unsubstituted cyclic sulfone group, and a halogen-substituted or unsubstituted cyclic carbonate group; R1, R2, R4, R5 1 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group or an ether alkyl group; n1 is any integer from 1 to 6, and can be 1 or 2.

2. The silicon-containing compound according to claim 1, characterized in that R3 includes at least one of the following groups: One or more of Among them, R5 2 、R5 3 、R5 4 、R5 5 、R5 6 Each independently includes hydrogen, halogen substituted or unsubstituted C1-C 10 Saturated or unsaturated alkyl, halogen substituted or unsubstituted C6-C 60 At least one of an aryl group, a carbonyl group, a carboxyl group, an ester group, a cyano group or an ether alkyl group; n2 is any integer from 1 to 6, and can be 1 or 2.

3. The silicon-containing compound according to claim 1 or 2, characterized in that R1, R2, R4, R5 1 Each independently includes at least one of hydrogen, halogen-substituted or unsubstituted C1-C3 alkyl.

4. The silicon-containing compound according to claim 1 or 2, characterized in that The compound represented by Formula I includes at least one of Compound A11 to Compound A20:

5. An electrolyte for a secondary battery, characterized in that: The electrolyte contains the silicon-containing compound according to any one of claims 1 to 4.

6. The electrolyte according to claim 5, characterized in that In the electrolyte, based on the total mass of the electrolyte, the mass content of the silicon-containing compound is less than or equal to 30%, and can be optionally 0.3%-10%.

7. The electrolyte according to claim 5 or 6, characterized in that The electrolyte further comprises a fluorinated cyclic carbonate; optionally, the fluorinated cyclic carbonate comprises one or more of fluorinated ethylene carbonate, difluoroethylene carbonate, trifluoropropylene carbonate, 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3-dioxolane-2-one, and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolane-2-one.

8. The electrolyte according to any one of claims 5 to 7, characterized in that Based on the total mass of the electrolyte, the mass content of the fluorinated cyclic carbonate is 2%-20%, and can be optionally 5%-15%.

9. The electrolyte according to any one of claims 5 to 8, characterized in that The electrolyte also includes one or more of chain esters, fluorine-free cyclic esters, and ethers, which can be selected from one or more of diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, tetrahydrofuran, dimethyl ether, diethyl ether, and ethylene glycol dimethyl ether.

10. A secondary battery, characterized in that: The electrolyte comprising the electrolyte described in any one of claims 5 to 9.

11. The secondary battery according to claim 10, characterized in that: The secondary battery includes a negative electrode active material, and the negative electrode active material includes a silicon-based material; Optionally, the silicon-based material includes one or more of elemental silicon, silicon-oxygen material, and silicon-carbon material; Optionally, based on the total mass of the negative electrode active material, the mass content of the silicon-based material is greater than or equal to 10%, and more optionally 20%-50%.

12. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to claim 10 or 11.

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