WO2018120791A1 - Electrolyte and secondary battery - Google Patents

Abstract

An electrolyte and a secondary battery. The electrolyte comprises an electrolyte salt, an organic solvent, and an additive. The additive comprises silyl sulfate, dinitrile compound and/or trinitrile compound. When the electrolyte is applied in the secondary battery, the storage performance of the secondary battery at a high temperature and circulation performance at a high temperature may be simultaneously improved under the synergy of said substances.

Description

Electrolyte and secondary battery Technical field

The present invention relates to the field of battery technologies, and in particular, to an electrolyte and a secondary battery.

Background technique

With the increasing use of electronic products such as smart phones, notebook computers and tablet computers, lithium ion secondary batteries, as the working power source for electronic products, have the characteristics of high energy density, no memory effect, high working voltage, etc., and are gradually replacing the traditional Ni-Cd, MH-Ni battery. However, with the expansion of the demand for electronic products and the development of power and energy storage equipment, the demand for lithium ion secondary batteries has been continuously improved. It has become a top priority to develop lithium ion secondary batteries with high energy density and satisfying rapid charge and discharge. At present, an effective method is to increase the voltage of the electrode active material, the compaction density, and the selection of a suitable electrolyte.

At present, lithium-ion secondary batteries widely used in electrolytes include lithium hexafluorophosphate as a conductive lithium salt and a mixture of a cyclic carbonate and a chain carbonate. However, the above electrolyte still has many disadvantages, particularly at a high voltage. Under the lithium ion secondary battery, the performance is poor, such as poor cycle performance, poor high temperature storage performance, poor safety performance, and poor rate performance.

Summary of the invention

In view of the problems in the background art, an object of the present invention is to provide an electrolyte and a secondary battery capable of simultaneously improving high-temperature storage performance and high-temperature cycle performance of a secondary battery when the electrolyte is applied to a secondary battery. .

In order to achieve the above object, in one aspect of the invention, the present invention provides an electrolyte comprising an electrolyte salt, an organic solvent, and an additive. The additive includes a silyl sulfate and a dinitrile compound and/or a trinitrile compound.

In another aspect of the invention, the invention provides a secondary battery comprising an electrolyte according to an aspect of the invention.

Advantageous effects of the present invention include, but are not limited to: relative to the prior art:

The electrolyte of the present invention includes both a silane-based sulfate and a dinitrile compound and/or a trinitrile compound, and when applied to a secondary battery, the high-temperature storage performance of the secondary battery can be simultaneously improved by the synergistic action of the above substances. And high temperature cycle performance.

detailed description

Hereinafter, the electrolytic solution and the secondary battery according to the present invention will be described in detail.

First, the electrolytic solution according to the first aspect of the invention will be explained.

The electrolytic solution according to the first aspect of the invention includes an electrolyte salt, an organic solvent, and an additive. The additive includes a silyl sulfate and a dinitrile compound and/or a trinitrile compound.

In the electrolytic solution according to the first aspect of the invention, the silane-based sulfate has a high reduction potential, and the high-temperature cycle performance of the secondary battery can be improved. The dinitrile compound and the trinitrile compound are easily complexed with the positive electrode to reduce the side reaction at high temperature and inhibit the high temperature gas generation of the secondary battery. However, since the nitrile group has strong electron absorption characteristics, it is easy to obtain an electron reduction reaction at the negative electrode. Moreover, the unstable product of the reduction product is deposited on the negative electrode, which affects the cycle performance of the secondary battery. When the above-mentioned substance is contained in the electrolyte, since the silyl sulfate preferentially forms a film on the surface of the negative electrode, the side reaction of the dinitrile compound and/or the trinitrile compound in the negative electrode can be suppressed, and therefore, under the synergistic action of the above substances, At the same time, the high-temperature storage performance and high-temperature cycle performance of the secondary battery are improved. In the electrolytic solution according to the first aspect of the invention, the silyl sulfate may be selected from one or more of the compounds represented by Formula 1. Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently selected from an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and a carbon number of One of an alkynyl group of 2 to 5 and an alkoxy group having 1 to 5 carbon atoms, and an H atom of an alkyl group, an alkenyl group, an alkynyl group or an alkoxy group may be further represented by F, Cl, Br, I, One or more substitutions of a cyano group, a carboxyl group, or a sulfonic acid group.

In the electrolytic solution according to the first aspect of the present invention, specifically, the silyl sulfate may be selected from the group consisting of bis(trimethylsilyl) sulfate, bis(triethylsilyl) sulfate, and double ( Tri-n-propylsilyl)sulfate, bis(triisopropylsilyl)sulfate, bis(tri-n-butylsilyl)sulfate, bis(triisobutylsilyl)sulfate, double (three uncle Butylsilyl) sulfate, bis(trimethoxysilyl) sulfate, bis(triethoxy) Silicate) sulfate, bis(tri-n-propoxysilyl)sulfate, bis(triisopropoxysilyl)sulfate, bis(tri-n-butoxysilyl)sulfate, bis(tri-sec-butyl) Oxysilyl) sulfate, bis(tri-tert-butoxysilyl) sulfate, bis(trifluoromethylsilyl)sulfate, trimethylsilyltriethylsilylsulfate, bis(triethylene) One or more of a sulphate-based sulphate or bis(triethynylsilyl) sulphate.

In the electrolytic solution according to the first aspect of the invention, the dinitrile compound may be selected from one or more of the compounds represented by Formula 2. In Formula 2, R _{7 is} selected from the group consisting of an alkylene group having 1 to 20 carbon atoms, a halogenated alkylene group having 1 to 20 carbon atoms, an alkyleneoxy group having 1 to 20 carbon atoms, and a carbon atom. The number is a halogenated alkyleneoxy group of 1 to 20, an alkenylene group having 2 to 20 carbon atoms, or a halogenated alkenylene group having 2 to 20 carbon atoms. Wherein, the halogen atom may be selected from one or more of F, Cl, Br, and I.

NC——R ₇ ——CN type 2

In the electrolytic solution according to the first aspect of the present invention, preferably, R _{7 is} selected from the group consisting of an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, and a carbon number. An alkyleneoxy group of 1 to 10, a haloalkyleneoxy group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or a halogenated alkenylene group having 2 to 10 carbon atoms. One of them, wherein, preferably, the halogen atom may be selected from one or more of F, Cl, and Br.

In the electrolytic solution according to the first aspect of the invention, in the formula 2, the number of oxygen atoms in the alkyleneoxy group or the haloalkyleneoxy group may be one, two or more.

In the electrolytic solution according to the first aspect of the present invention, specifically, the dinitrile compound may be selected from the group consisting of malononitrile, succinonitrile, 2-methylsuccinonitrile, tetramethylsuccinonitrile, and pentane Nitrile, 2-methylglutaronitrile, adiponitrile, fumaronitrile, 2-methyleneglutaronitrile, 3,5-dioxa-heptonitrile, ethylene glycol bis(2-cyanoethyl) Ether, diethylene glycol bis(2-cyanoethyl) ether, triethylene glycol bis(2-cyanoethyl) ether, tetraethylene glycol bis(2-cyanoethyl) ether, 1 , 2-bis(2-cyanoethoxy)ethane, 1,3-bis(2-cyanoethoxy)propane, 1,4-bis(2-cyanoethoxy)butane, 1, 5-bis(2-cyanoethoxy)pentane, ethylene glycol bis(4-cyanobutyl)ether, 1,6-dicyanohexane, 1,2-dibromo-2,4- One or more of dicyanbutane.

In the electrolytic solution according to the first aspect of the invention, the trinitrile compound may be selected from one or more of the compounds represented by Formula 3. In Formula 3, R ₈ and R ₉ are each independently selected from an alkylene group having 1 to 20 carbon atoms, an alkyleneoxy group having 1 to 20 carbon atoms, and a halogenated group having 1 to 20 carbon atoms. An alkylene group, a halogenated alkyleneoxy group having 1 to 20 carbon atoms, an alkenylene group having 2 to 20 carbon atoms, or a halogenated alkenylene group having 2 to 20 carbon atoms. Among them, the halogen atom may be selected from one or more of F, Cl, Br, and I.

In the electrolytic solution according to the first aspect of the present invention, preferably, R ₈ and R ₉ are each independently selected from an alkylene group having 1 to 10 carbon atoms and an alkylene oxide having 1 to 10 carbon atoms. a group, a halogenated alkylene group having 1 to 10 carbon atoms, a halogenated alkyleneoxy group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, and 2 to 10 carbon atoms. One of the haloalkenylene groups, wherein, preferably, the halogen atom may be selected from one or more of F, Cl, and Br.

In the electrolytic solution according to the first aspect of the invention, in the formula 3, the number of oxygen atoms in the alkyleneoxy group or the haloalkyleneoxy group may be one, two or more.

In the electrolytic solution according to the first aspect of the present invention, specifically, the trinitrile compound may be selected from the group consisting of 1,3,6-hexanetrizonitrile, 1,2,3-propanetricarbonitrile, 1,3, One or more of 5-pentane tricarbonitrile.

In the electrolytic solution according to the first aspect of the invention, in Formula 3, R ₈ and R ₉ form a cyclic structure, that is, the trinitrile compound has a cyclic structure. Specifically, the trinitrile compound may be selected from one or both of 1,3,5-benzenetriazonitrile and 1,3,5-cyclohexanetricarbonitrile.

In the electrolyte according to the first aspect of the present invention, the content of the silane-based sulfate may be 0.5% to 10% of the total weight of the electrolyte, and preferably, the content of the silane-based sulfate may be The total weight of the electrolyte is from 1% to 5%.

In the electrolytic solution according to the first aspect of the invention, the total content of the dinitrile compound and/or the trinitrile compound may be from 0.5% to 10% by weight based on the total weight of the electrolytic solution, preferably, the dinitrile The total content of the compound and/or trinitrile compound may range from 1% to 5% of the total weight of the electrolyte.

In the electrolytic solution according to the first aspect of the invention, the electrolyte salt may be selected from a lithium salt, a sodium salt or a zinc salt, which varies depending on the secondary battery to which the electrolyte is applied.

In the electrolytic solution according to the first aspect of the present invention, the content of the electrolyte salt is 6.2% to 25% of the total weight of the electrolytic solution, and preferably, the content of the electrolyte salt is the electrolytic solution. The total weight is from 6.25% to 18.8%, and further preferably, the content of the electrolyte salt is from 10% to 15% of the total weight of the electrolyte.

In the electrolytic solution according to the first aspect of the present invention, the specific kind of the organic solvent is not There are special restrictions, which can be selected according to actual needs. Preferably, a non-aqueous organic solvent is used. The non-aqueous organic solvent may include any kind of carbonate, carboxylate. The carbonate may include a cyclic carbonate or a chain carbonate. The non-aqueous organic solvent may also include a halogenated compound of a carbonate. Specifically, the organic solvent may be selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, pentylene carbonate, fluoroethylene carbonate, dimethyl carbonate (DMC), Diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl formate, ethyl formate, ethyl acetate, propyl propionate, ethyl propionate, γ-butyrolactone (BL One or more of tetrahydrofuran (THF).

In the electrolytic solution according to the first aspect of the present invention, it is to be noted that "alkyl", "alkenyl", "alkynyl", "alkoxy", "alkylene" appearing in the specification, "Haloalkylene", "alkoxy", "haloalkyleneoxy", "alkenylene", "haloalkenylene" and the like may be either a chain structure or a ring shape. structure.

Next, a secondary battery according to a second aspect of the invention will be described.

A secondary battery according to a second aspect of the invention includes the electrolytic solution according to the first aspect of the invention.

In the secondary battery according to the second aspect of the invention, the secondary battery further includes: a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet includes a positive electrode current collector and a positive electrode film disposed on the positive electrode current collector, and the positive electrode film includes a positive electrode active material, a binder, and a conductive agent. The negative electrode sheet includes a negative electrode current collector and an negative electrode film disposed on the negative electrode current collector, and the negative electrode film includes a negative electrode active material, a binder, and may also include a conductive agent. The separator is spaced between the positive electrode tab and the negative electrode tab.

In the secondary battery according to the second aspect of the invention, the separator may be any separator material used in the existing secondary battery, such as polyethylene, polypropylene, polyvinylidene fluoride, and multilayers thereof. Composite membranes, but are not limited to these.

In the secondary battery according to the second aspect of the invention, the secondary battery may be a lithium ion secondary battery, a sodium ion secondary battery, or a zinc ion secondary battery.

When the secondary battery is a lithium ion secondary battery, the electrolyte salt may be selected from a lithium salt, and the lithium salt may be selected from the group consisting of LiPF ₆ , LiBF ₄ , LiFSI, LiTFSI, LiClO ₄ , LiAsF ₆ , LiBOB, LiDFOB, LiPO. _{One or more of 2} F ₂ , LiTFOP, LiN(SO ₂ RF) ₂ , LiN(SO ₂ F)(SO ₂ RF), wherein RF=C _n F _2n+1 represents a saturated perfluoroalkyl group , n is an integer within 1 to 10. Preferably, the lithium salt is LiPF ₆ .

When the secondary battery is a lithium ion secondary battery, the positive electrode active material may be selected from lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), spinel-type LiMn ₂ O ₄ , olivine-type LiMPO ₄ , one of ternary positive electrode materials LiNi _x A _y B _(1-xy) O ₂ and Li _1-x' (A'_y'B'_z' C _1-y'-z' ) O ₂ or Several. Wherein, in the olivine-type LiMPO ₄ , M is selected from one or more of Co, Ni, Fe, Mn, and V; and in the ternary positive electrode material LiNi _x A _y B _(1-xy) O ₂ , A and B are each independently selected from one of Co, Al, and Mn, and A and B are not the same, 0<x<1, 0<y<1 and x+y<1; in the ternary positive electrode material Li _{1 -x'} (A'_y'B'_z' C _1-y'-z' ) In O ₂ , A', B', and C are each independently selected from one of Co, Ni, Fe, and Mn, 0 <x'<1, 0≤y'<1, 0≤z'<1 and y'+z'<1, and A', B', and C are different.

When the secondary battery is a lithium ion secondary battery, the anode active material may be selected from metallic lithium. The negative active material may also be selected from materials capable of intercalating lithium at <2 V (vs. Li/Li ⁺ ). Specifically, the negative active material may be selected from natural graphite, artificial graphite, mesophase micro carbon spheres ( Abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO ₂ , spinel structure lithiated TiO ₂ -Li ₄ One or more of Ti ₅ O ₁₂ and Li-Al alloy.

When the secondary battery is a sodium ion secondary battery or a zinc ion secondary battery, it is only necessary to change the corresponding positive electrode active material, negative electrode active material, and electrolyte salt.

The present application is further illustrated below in conjunction with the embodiments. It is to be understood that the examples are not intended to limit the scope of the application. Only the case where the secondary battery is a lithium ion secondary battery is shown in the embodiment, but the invention is not limited thereto.

In the following examples, the materials, reagents, and instruments used were commercially available unless otherwise specified.

For ease of explanation, the additives used in the following examples are abbreviated as follows:

A1: bis(trifluoromethylsilyl) sulfate

A2: trimethylsilyltriethylsilyl sulfate

B1:1,2-di(2-cyanoethoxy)ethane

B2: 1,3,6-hexane tricarbonitrile

The lithium ion secondary batteries of Examples 1 to 11 and Comparative Examples 1 to 4 were all produced in the following manner. Ready.

(1) Preparation of positive electrode sheets

The positive electrode active material lithium cobaltate (LiCoO ₂ ), the binder polyvinylidene fluoride, and the conductive agent acetylene black were mixed at a weight ratio of 98:1:1, and N-methylpyrrolidone (NMP) was added under the action of a vacuum mixer. Stir the system to a uniform transparency to obtain a positive electrode slurry; uniformly apply the positive electrode slurry to a positive electrode current collector aluminum foil having a thickness of 12 μm; dry the aluminum foil at room temperature, transfer it to an oven at 120 ° C for 1 hour, and then pass cold pressing. The positive electrode sheets were obtained by slitting.

(2) Preparation of negative electrode sheets

The negative electrode active material artificial graphite, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber were mixed at a weight ratio of 98:1:1, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum mixer. The negative electrode slurry was uniformly coated on a negative electrode current collector copper foil having a thickness of 8 μm; the copper foil was air-dried at room temperature, transferred to an oven at 120 ° C for 1 hour, and then subjected to cold pressing and slitting to obtain a negative electrode sheet.

(3) Electrolyte preparation

In an argon atmosphere glove box with a water content of <10 ppm, EC, PC, and DEC were mixed at a volume ratio of EC:PC:DEC=1:1:1, and then the sufficiently dried lithium salt LiPF _{6 was} dissolved in the mixed organic In the solvent, a silyl sulfate, a dinitrile compound, and a trinitrile compound are added, and the mixture is uniformly mixed to obtain an electrolytic solution. Wherein, the content of LiPF ₆ is 12.5% of the total weight of the electrolyte. The specific types and contents of the silyl sulfate, the dinitrile compound, and the trinitrile compound used in the electrolytic solution are shown in Table 1. In Table 1, the content of the silyl sulfate, the dinitrile compound, and the trinitrile compound is a weight percentage calculated based on the total weight of the electrolytic solution.

(4) Preparation of separator

A 16 μm thick polypropylene separator (model C210, supplied by Celgard) was used.

(5) Preparation of lithium ion secondary battery

The positive electrode sheet, the separator film and the negative electrode sheet are stacked in order, so that the separator is in a role of isolation between the positive and negative electrode sheets, and then wound to obtain a bare cell; the bare cell is placed in the outer packaging foil, The prepared electrolyte solution is injected into the dried bare cell, and subjected to vacuum encapsulation, standing, formation, shaping, and the like to obtain a lithium ion secondary battery.

Table 1 Additives and contents of Examples 1-11 and Comparative Examples 1-4

Note: "-" means not added.

Next, the test process of the lithium ion secondary battery will be described.

(1) High temperature cycle performance test of lithium ion secondary battery

The lithium ion secondary battery was charged at a constant current of 1 C to a voltage of 4.45 V at 45 ° C, further charged at a constant voltage of 4.45 V until the current was 0.05 C, and then discharged at a constant current of 1 C to a voltage of 3.0 V. A charge and discharge cycle, this discharge capacity is the discharge capacity of the first cycle. The lithium ion secondary battery was subjected to 300 cycles of charge/discharge test in accordance with the above method, and the discharge capacity at the 300th cycle was detected.

The capacity retention ratio (%) of the lithium ion secondary battery after circulating at 45 ° C for 300 times = (discharge capacity of 300 cycles of lithium ion secondary battery discharge / discharge capacity of the first cycle of lithium ion secondary battery) × 100%. In the above test procedure, 15 lithium ion secondary batteries were tested in each group and averaged.

(2) High-temperature storage performance test of lithium ion secondary battery

The lithium ion secondary battery was charged at a constant current of 0.5 C to a voltage of 4.45 V at 25 ° C, and then charged at a constant voltage of 4.45 V until the current was 0.05 C. At this time, the thickness of the lithium ion secondary battery was tested and recorded as h. _0; after the lithium ion secondary battery is placed in a thermostat 60 deg.] C, removed after 30 days storage, the thickness of the test case and a lithium ion secondary battery is referred to as h _1.

The thickness expansion ratio of the lithium ion secondary battery after storage at 60 ° C for 30 days = [(h ₁ -h ₀ ) / h ₀ ] × 100%. In the above test procedure, 15 lithium ion secondary batteries were tested in each group and averaged.

Table 2 Test results of Examples 1-11 and Comparative Examples 1-4

Capacity retention after 300 cycles at 45 ° C Thickness expansion rate after storage at 60 ° C for 30 days Example 1 61.2% 15.3% Example 2 56.1% 15.9% Example 3 72.5% 14.8% Example 4 86.1% 15.1% Example 5 85.9% 15.8% Example 6 60.5% 20.1% Example 7 58.3% 7.5% Example 8 55.9% 5.8% Example 9 48.8% 3.2% Example 10 58.0% 7.4% Example 11 58.3% 9.8% Comparative example 1 30.4% 45.5% Comparative example 2 60.3% 45.1% Comparative example 3 31.8% 15.6% Comparative example 4 27.1% 8.0%

From the relevant data analysis in Table 2, it can be known that the silane-based sulfate and the dinitrile compound and/or the trinitrile compound are not added in Comparative Example 1, and the high-temperature cycle performance and high-temperature storage performance of the lithium ion secondary battery are poor; When only the silane-based sulfate was added to the electrolyte (Comparative Example 2), the high-temperature cycle performance of the lithium ion secondary battery was significantly improved, but the high-temperature storage performance did not change significantly; when the dinitrile compound was added to the electrolyte (Comparative Example 3) High-temperature storage performance of lithium ion secondary batteries The improvement was improved, but the high-temperature cycle performance was still poor, and when the content of the dinitrile compound was increased (Comparative Example 4), the high-temperature cycle property was remarkably deteriorated.

When the silyl sulfate and the dinitrile compound and/or the trinitrile compound (Examples 1 to 11) were simultaneously added to the electrolytic solution, the high-temperature cycle performance and high-temperature storage performance of the lithium ion secondary battery were improved.

Claims (10)

An electrolyte comprising: Electrolyte salt Organic solvent; additive; It is characterized in that The additive includes: Silyl sulfate; A dinitrile compound and/or a trinitrile compound. The electrolyte according to claim 1, wherein the silane-based sulfate is selected from one or more of the compounds represented by Formula 1;

among them, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently selected from an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and 2 to 2 carbon atoms. One of an alkynyl group of 5 and an alkoxy group having 1 to 5 carbon atoms, and an H atom of an alkyl group, an alkenyl group, an alkynyl group or an alkoxy group may be further represented by F, Cl, Br, I or a cyano group. One or several substitutions of a carboxyl group or a sulfonic acid group. The electrolyte according to claim 2, wherein said silane-based sulfate is selected from the group consisting of bis(trimethylsilyl) sulfate, bis(triethylsilyl) sulfate, and bis(tri-n-propyl) Silicate, bis(triisopropylsilyl)sulfate, bis(tri-n-butylsilyl)sulfate, bis(triisobutylsilyl)sulfate, bis(tri-tert-butylsilyl) Sulfate, bis(trimethoxysilyl)sulfate, bis(triethoxysilyl)sulfate, bis(tri-n-propoxysilyl)sulfate, bis(triisopropoxysilyl) Sulfate, bis(tri-n-butoxysilyl) sulfate, bis(tri-sec-butoxysilyl) sulfate, bis(tri-tert-butoxysilyl) sulfate, bis(trifluoromethylsilyl) One or more of sulfate, trimethylsilyltriethylsilylsulfate, bis(trivinylsilyl)sulfate, bis(triethynylsilyl)sulfate. The electrolyte according to claim 1, wherein The dinitrile compound is selected from one or more of the compounds represented by Formula 2; NC——R ₇ ——CN type 2 In Formula 2, R _{7 is} selected from the group consisting of an alkylene group having 1 to 20 carbon atoms, a halogenated alkylene group having 1 to 20 carbon atoms, an alkyleneoxy group having 1 to 20 carbon atoms, and a carbon atom. a halogenated alkyleneoxy group having 1 to 20, an alkenylene group having 2 to 20 carbon atoms, or a halogenated alkenylene group having 2 to 20 carbon atoms, wherein the halogen atom is selected from the group consisting of F and Cl. One or several of Br, I; The trinitrile compound is selected from one or more of the compounds represented by Formula 3:

In Formula 3, R ₈ and R ₉ are each independently selected from an alkylene group having 1 to 20 carbon atoms, an alkyleneoxy group having 1 to 20 carbon atoms, and a halogenated group having 1 to 20 carbon atoms. An alkylene group, a halogenated alkyleneoxy group having 1 to 20 carbon atoms, an alkenylene group having 2 to 20 carbon atoms, or a halogenated alkenylene group having 2 to 20 carbon atoms; The atom is selected from one or more of F, Cl, Br, and I. The electrolyte according to claim 4, wherein In Formula 2, R _{7 is} selected from the group consisting of an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkyleneoxy group having 1 to 10 carbon atoms, and a carbon atom. a halogenated alkyleneoxy group having 1 to 10, an alkenylene group having 2 to 10 carbon atoms, and a halogenated alkenylene group having 2 to 10 carbon atoms, wherein the halogen atom is selected from the group consisting of F One or more of Cl, Br; In Formula 3, R ₈ and R ₉ are each independently selected from an alkylene group having 1 to 10 carbon atoms, an alkyleneoxy group having 1 to 10 carbon atoms, and a halogenated group having 1 to 10 carbon atoms. An alkylene group, a halogenated alkyleneoxy group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or a halogenated alkenylene group having 2 to 10 carbon atoms, wherein The halogen atom is selected from one or more of F, Cl, and Br. The electrolyte according to claim 5, wherein The dinitrile compound is selected from the group consisting of malononitrile, succinonitrile, 2-methylsuccinonitrile, tetramethylsuccinonitrile, glutaronitrile, 2-methylglutaronitrile, adiponitrile, and fumaronitrile , 2-methylene glutaronitrile, 3,5-dioxa-peptonitrile, ethylene glycol bis(2-cyanoethyl) ether, diethylene glycol bis(2-cyanoethyl) ether , triethylene glycol bis(2-cyanoethyl) ether, tetraethylene glycol bis(2-cyanoethyl) ether, 1,2-bis(2-cyanoethoxy)ethane, 1,3 - bis(2-cyanoethoxy)propane, 1,4-bis(2-cyanoethoxy)butane, 1,5-bis(2-cyanoethoxy)pentane, ethylene glycol One or more of bis(4-cyanobutyl)ether, 1,6-dicyanohexane, and 1,2-dibromo-2,4-dicyanobutane; The trinitrile compound is selected from one or more of 1,3,6-hexanetrizonitrile, 1,2,3-propanetricarbonitrile, and 1,3,5-pentanetricarbonitrile. The electrolytic solution according to claim 4, wherein in Formula 3, R ₈ and R ₉ form a cyclic structure. The electrolytic solution according to claim 7, wherein the trinitrile compound is one or more selected from the group consisting of 1,3,5-benzenetrizonitrile and 1,3,5-cyclohexanetricarbonitrile. The electrolyte according to claim 1, wherein The content of the silyl sulfate is 0.5% to 10% of the total weight of the electrolyte, preferably, the content of the silyl sulfate is 1% to 5% of the total weight of the electrolyte; The total content of the dinitrile compound and/or the trinitrile compound is 0.5% to 10% of the total weight of the electrolyte, preferably, the total content of the dinitrile compound and/or the trinitrile compound is the electrolysis 1% to 5% of the total weight of the liquid. A secondary battery comprising the electrolytic solution according to any one of claims 1-9.