KR20200049682A - Gel polymer electrolyte and electrochemical capaciter comprising the same - Google Patents

Abstract

A gel polymer electrolyte according to one embodiment of the present invention includes an electrolyte additive capable of improving rate capability and improving a lifespan characteristic at high voltage. Specifically, the electrolyte additive includes a compound represented by chemical formula 1 below.

Description

Gel polymer electrolyte and an electrochemical capacitor comprising the same {GEL POLYMER ELECTROLYTE AND ELECTROCHEMICAL CAPACITER COMPRISING THE SAME}

It relates to a gel polymer electrolyte and an electrochemical capacitor comprising the same.

Recently, as interest in energy storage and conversion technology has increased, attention has been focused on various types of electrochemical capacitors.

Liquid electrolytes are widely used in electrochemical capacitors, but there is a problem that the driving becomes unstable under conditions such as high temperature and high voltage due to solvent volatile and instability.

To solve this problem, a technique of applying a gel polymer electrolyte in place of a liquid electrolyte has been studied.

However, the gel polymer electrolyte, which is generally known, has a limitation in that electrochemical properties are inferior to conventional liquid electrolytes. As a result, generally known gel polymer electrolytes are more unsuitable for supercapacitors that require higher output characteristics than lithium ion batteries.

An embodiment of the present invention provides a gel polymer electrolyte and an electrochemical capacitor including the same, which simultaneously achieve high rate capability improvement and life characteristic improvement.

The gel polymer electrolyte according to an embodiment of the present invention includes an electrolyte additive capable of simultaneously achieving high rate capability and improving life characteristics at high voltage.

Specifically, the electrolyte additive includes a compound represented by Formula 1 below.

[Formula 1]

(In the formula (1), R ¹ to R ⁴ each represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 13.)

The electrolyte additive includes a compound represented by Formula 2 below.

[Formula 2]

(In Formula 2, R ⁵ represents hydrogen or an alkyl group.

R ⁶ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.)

The compound represented by Chemical Formula 2 may be represented by Chemical Formula 3 below.

[Formula 3]

(In the formula (3), R ⁷ represents hydrogen or an alkyl group.

R ⁸ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.

X represents an alkylene group having 1 to 6 carbon atoms.

m represents an integer from 1 to 22.)

In Formula 1, R ¹ and R ² are each a hydrogen or methyl group, and R ³ and R ⁴ may be hydrogen.

In Formula 1, n may represent an integer from 1 to 4.

In Formula 3, R ⁷ and R ⁸ are each a hydrogen or methyl group, and X may be -CH _2- .

It may contain 1 to 8% by weight of electrolyte additives.

The weight ratio of the compound represented by Formula 1 and the compound represented by Formula 2 may be 1: 1 to 3: 1.

The gel polymer electrolyte according to an embodiment of the present invention includes an acetonitrile solvent and an electrolyte salt.

The electrochemical capacitor according to an embodiment of the present invention includes the gel polymer electrolyte described above.

Anode and cathode; It may include a gel polymer electrolyte interposed between the positive electrode and the negative electrode and a polymer film formed on the surface of at least one of the positive electrode and the negative electrode.

By using a gel polymer electrolyte in one embodiment of the present invention, it is possible to realize high capacitance through stabilizing life characteristics at a high driving voltage and improving rate capability.

By using a gel polymer electrolyte in one embodiment of the present invention, it is possible to secure a high driving voltage.

1 is a graph measuring an open circuit voltage over time in Experimental Example 1.
2 is a graph measuring the ion conductivity in Experimental Example 2.
FIG. 3 is a graph measuring capacitance for charge / discharge rate in Experimental Example 3.
4 is a graph measuring capacitance for each cycle in Experimental Example 4.
5 is a graph measuring capacitance recovery rate in Experimental Example 4.
6 is a graph measuring voltage between positive and negative electrodes for each cycle in Experimental Example 4.
7 is a graph measuring the EIS resistance before and after the bulk cycle in Experimental Example 5.
8 is a graph measuring the EIS resistance before and after the cycle of the interface in Experimental Example 5.
9 and 10 is a graph measuring the charge and discharge performance by rate in Experimental Example 6.

In the present specification, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless specifically stated otherwise. The terms "about", "substantially", and the like, as used throughout this specification, are used in or at a value close to that value when manufacturing and material tolerances specific to the stated meaning are given, and are understood herein. To aid, accurate or absolute figures are used to prevent unscrupulous use of the disclosed disclosure by unscrupulous infringers. The term “~ (step)” or “step of” as used in the present specification does not mean “step for”.

In this specification, the term "combination of these" included in the expression of the marki form means one or more mixtures or combinations selected from the group consisting of the elements described in the expression of the marki form, the components It means to include one or more selected from the group consisting of.

"Substitution" in the present specification, unless otherwise defined, at least one hydrogen of the compound is a C1 to C30 alkyl group; C1 to C10 alkoxy groups; Silane group; Alkylsilane groups; Alkoxysilane group; It means substituted with ethyleneoxyl group.

"Hetero" as used herein means an atom selected from the group consisting of N, O, S, and P, unless otherwise defined.

The alkyl group may be a C1 to C20 alkyl group, specifically, a C1 to C6 lower alkyl group, a C7 to C10 intermediate alkyl group, or a C11 to C20 higher alkyl group.

For example, a C1 to C4 alkyl group means that there are 1 to 4 carbon atoms in the alkyl chain, which are methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl. Indicates that it is selected from the group consisting of

Typical alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group. .

Based on the above definition, embodiments of the present invention will be described in detail. However, these are presented as examples, and the present invention is not limited thereby, and the present invention is only defined by the scope of claims to be described later.

The gel polymer electrolyte according to an embodiment of the present invention includes an electrolyte additive capable of improving a high rate capacity. Therefore, when using the gel polymer electrolyte according to an embodiment of the present invention, a high capacitance can be realized and a high driving voltage can be secured.

Specifically, in one embodiment of the present invention, high-rate capacity means an ability to improve a phenomenon in which the capacitance is reduced as the charge / discharge speed increases due to a difference in the relative mobility of ions and electrons.

Specifically, the additive may include a compound represented by Formula 1 below.

[Formula 1]

(In the formula (1), R ¹ to R ⁴ each represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 13.)

In one embodiment of the present invention, a monomer having two acrylate or methacrylate groups per molecule is used. As such, by using a monomer having two acrylate or methacrylate groups per molecule, sufficient gelation can be induced to improve physical performance as a gel polymer electrolyte and to increase the rate of charge and discharge, thereby increasing the rate of charge and discharge.

In one embodiment of the present invention, a substituted or unsubstituted poly (ethylene oxy group) is used as a linking group between acrylate or methacrylate groups. Substituted or unsubstituted poly (ethylene oxy group) is advantageous in that it can improve the ionic conductivity of the polymer electrolyte.

In the formula (1), R ¹ to R ⁴ each represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. Specifically, R ¹ and R ² are each a hydrogen or methyl group, and R ³ and R ⁴ may be hydrogen.

In the formula (1), n represents an integer from 1 to 13. If n is too long, it may be difficult to induce proper electrochemical performance of monomers and polymers because additives between active materials and even between active material pores may not be impregnated. More specifically, n may be an integer from 1 to 4. More specifically, n may be 2 or 3.

When a compound in which n is different is used in combination, n means an average (number average) n value.

The electrolyte additive may be a one-component system or a multi-component system including two or more components.

In the case of a multi-component system, a compound represented by the following Chemical Formula 2 may be further included in addition to the compound represented by the above Chemical Formula 1.

The electrolyte additive may be a one-component system or a multi-component system including two or more components.

The electrolyte additive includes two components, and the weight ratio between components may be 1: 1 to 3: 1. When the weight ratio between components is too low, that is, less than 1: 1, when gel polymerizing, a problem that gelation does not proceed may occur. When the weight ratio between components is too high, i.e., greater than 3: 1, when gel polymerizing, a problem of reduction in hardness and ionic conductivity may occur. More specifically, it may be 1.1: 1 to 2.9: 1. More specifically, it may be from 1.2: 1 to 2.8: 1. More specifically, it may be 1.3: 1 to 2.7: 1. More specifically, it may be 1.5: 1 to 2.5: 1.

The type of the electrolyte additive added may include an acrylate-based or methacrylate-based monomer. More specifically, the electrolyte additive may include an acrylate-based or methacrylate-based monomer represented by Chemical Formula 2 below.

[Formula 2]

(In Formula 2, R ⁵ represents hydrogen or an alkyl group.

R ⁶ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.)

The electrolyte additive may be in a gel polymer electrolyte state. In the case of a gel polymer electrolyte, it is advantageous in terms of high voltage, high life, durability at high temperatures, and prevention of leakage.

The acrylate-based or methacrylate-based monomer may contain 1 to 6 functional groups per molecule. If there are too many functional groups, a problem of reduction in hardness and ionic conductivity due to serious gelation may occur.

Functional groups include acrylate groups or methacrylate groups.

The acrylate-based or methacrylate-based monomer may include polyalkylene glycol or polyalkylene oxide. By containing polyalkylene glycol or polyalkylene oxide, it is advantageous in that the ion conductivity of the polymer electrolyte can be improved.

Specifically, the length of the polyalkylene glycol or polyalkylene oxide may be 1 to 22. When the length of the polyalkylene glycol or the polyalkylene oxide is too long, a problem that hardness and ion conductivity decrease due to severe gelation may occur. More specifically, the length of the polyalkylene glycol or polyalkylene oxide may be 3 to 15.

Specifically, the additive may further include an acrylate-based or methacrylate-based monomer represented by Chemical Formula 3 below.

[Formula 3]

(In Formula 3, R ⁷ represents hydrogen or an alkyl group.

R ⁸ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.

X represents an alkylene group having 1 to 6 carbon atoms.

m represents an integer from 1 to 22.)

More specifically, R ⁸ may be hydrogen, a straight-chain or branched alkyl group. m may represent an integer from 1 to 15.

More specifically, R ⁷ and R ⁸ are each a hydrogen or methyl group, and X may be -CH _2- . m may represent an integer from 2 to 8.

The additive may be included in an amount of 1 to 8% by weight based on 100% by weight of the electrolyte. If the additive is contained too much in the electrolyte, it may interfere with the exchange of electrons through the electrolyte and deteriorate the properties of the electrochemical capacitor. If the additive is included in the electrolyte too little, the effect of increasing the high-capacity capacity due to the additive may be insignificant and the characteristics of the electrochemical capacitor may be deteriorated. More specifically, the additive may be included 2 to 8% by weight. More specifically, the additive may be included 3 to 8% by weight. More specifically, the additive may be included 4 to 7% by weight.

When the electrolyte additive contains two or more types of components, the total amount of the additives may be included in the above-mentioned range.

The electrolytic solvent is used to dissolve or dissociate the electrolyte salt. Typically, the electrolytic solvent may be used alone or in combination of two or more of cyclic carbonate, linear carbonate, lactone, ether, ester, sulfoxide, acetonitrile, lactam, ketone and halogen derivatives thereof. Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), and examples of linear carbonates include diethyl carbonate (DEC) and dimethyl carbonate (DMC). ), Dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), and methyl propyl carbonate (MPC). Examples of lactones are gamma-butyrolactone (GBL), and examples of ethers are dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1, 2-diethoxy ethane. Examples of such esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl pivalate, and the like. In addition, the sulfoxide includes dimethyl sulfoxide, etc., the lactam includes N-methyl-2-pyrrolidone (NMP), and the ketone includes polymethylvinyl ketone. In addition, these halogen derivatives can also be used, and are not limited to the above-described exemplified electrolyte electrolytic solvents. Moreover, it is known that these electrolytic solvents can be used alone or in combination of two or more.

Among these, acetonitrile solvent used in one embodiment of the present invention has a lower dielectric constant than that of sulfolane and carbonate based solvents used in capacitor-based electrochemical capacitors, and thus has viscosity. Low, it is possible to prepare a gel polymer electrolyte to which a polymer having a relatively high content compared to the same curing degree is added. For other solvents, an electrolyte with a high degree of curing is formed even with a small amount of polymer, and at the same time, ionic conductivity due to a sharp increase in viscosity is rapidly reduced. Such a gel polymer electrolyte has only a high degree of hardening, and a sufficient amount of a polymer capable of increasing the advanced rate capability proposed in the present invention cannot be impregnated into the electrode, and the sharp reduction effect of ion conductivity has a synergistic effect of high rate capacity. It is difficult to expect to improve the overall cell performance because it has a greater effect.

The gel polymer electrolyte further includes an electrolyte salt. The electrolyte salt dissociates in the electrolytic solvent and acts as a component of ion conduction in the electrochemical capacitor, and may serve to promote the movement of cations between the anode and the cathode. For example, SBPBF ₄ (spirobipyrrolidinium tetrafluoroborate), TEABF ₄ , EMIBF4, TEMABF ₄ , LIPF ₆ , LiBF ₄ , LiTFSI, LiBETI, LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (CyF _{2y + 1} SO ₂ ) (where x, y is a natural number), LiCl, LiI, or a combination thereof. The content of the electrolyte salt in the gel polymer electrolyte is the number of moles (mol) with respect to the electrolytic solvent (L) in the electrolyte, and may be 0.5 to 3.0 M. In this case, the gel polymer electrolyte may have an appropriate viscosity as a gel form, and the electrolyte salt may be dissolved in an electrolytic solvent, contributing to effective movement of cations.

The electrochemical capacitor according to an embodiment of the present invention includes the above-described polymer electrolyte.

In one embodiment of the present invention, the electrochemical capacitor may be a supercapacitor (SC). Supercapacitors include an electrostatic double-layer capacitor, an electrochemical pseudocapacitor, and a hybrid capacitor.

Hereinafter, each configuration of the electrochemical capacitor will be described in detail. Hereinafter, a supercapacitor will be described as an example, but a person skilled in the art can easily divert the technical idea of adding an electrolyte additive to other capacitors.

The capacitor includes an electrode comprising a positive electrode and a negative electrode, and a gel polymer electrolyte.

As a positive electrode and a negative electrode active material that can be applied as an electrode active material, any carbon material having a double-layer capacity is possible, for example, activated carbon, activated carbon fiber, carbon aerogel, conductive polymer, metal oxide, natural fiber, amorphous carbon, flaren (fullerene), nanotubes and graphene (graphene) may be used, but is not limited thereto.

The two electrodes of the supercapacitor may be physically separated by the above-described gel polymer electrolyte, and at the same time, ionic connection may be made.

In one embodiment of the present invention, a polymer membrane is formed on the surface of at least one of the positive electrode and the negative electrode, thereby preventing further reaction of the electrolyte salt and smoothly operating at high voltage. That is, unnecessary faradic reactions are suppressed by the polymer membrane. The polymer film may be formed on only one of the positive electrode or the negative electrode, or the polymer film may be formed on both the positive electrode and the negative electrode. The surface of the electrode means the surface in the direction of the electrolyte.

The polymer membrane may include a polymer polymerized with an electrolyte additive. As the double bond in the electrolyte additive is broken, a continuous addition reaction occurs and the carbon chain is lengthened to form a polymer.

The polymer film may be formed to a thickness of 0.1 to 50 nm. If the thickness of the polymer film is too thin, the purpose of electrode protection may be difficult to achieve. If the thickness of the polymer film is too thick, the micropore of the electrode is blocked, and thus the specific surface area is greatly reduced and charge / discharge capacity may be reduced.

Since the gel polymer electrolyte has been described above, overlapping descriptions are omitted.

The method of manufacturing an electrochemical capacitor according to an embodiment of the present invention may be the following four methods.

Method 1: assembling the electrode and separator to produce an assembly; Impregnating the assembly with an electrolyte containing an electrolyte additive and no electrolyte salt; Sealing and curing; Injecting the electrolyte after disassembling the assembly; And sealing.

Method 2: assembling the electrode and separator to produce an assembly; Injecting an electrolyte containing an electrolyte additive and an electrolyte salt; Sealing and curing.

Method 3: coating or impregnating an electrolyte containing an electrolyte additive and an electrolyte salt on the electrode; Manufacturing an assembly by assembling the electrode and the separator; Sealing and curing.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

Comparative Example 1

Acetonitrile solvent in which SBPBF ₄ (spirobipyrrolidinium tetrafluoroborate) at a concentration of 1.0 M was dissolved was used as a basic electrolyte.

Comparative Example 2

To the electrolyte of Comparative Example 1, polyethylene glycol methyl methacrylate represented by the following formula (polyethylene glycol methyl methacrylate, PEGMEA, n is 4 or 5) was added 5% by weight to prepare an electrolyte.

Example 1

To the electrolyte of Comparative Example 1, ethylene glycol dimethacrylate (EGDMA) and PEGMEA represented by the following formula were added at a weight ratio of 3: 2, and the total amount added was added at 5% by weight to prepare an electrolyte.

Example 2

5% by weight of ethylene glycol dimethacrylate (EGDMA) was added to the electrolyte of Comparative Example 1 to prepare an electrolyte.

Comparative Example 3

An electrolyte was prepared by adding 10% by weight of ethylene glycol dimethacrylate (EGDMA) to the electrolyte of Comparative Example 1.

Comparative Example 4

An electrolyte was prepared by adding 15% by weight of ethylene glycol dimethacrylate (EGDMA) to the electrolyte of Comparative Example 1.

Comparative Example 5

The electrolyte of Comparative Example 1 was prepared by adding 5% by weight of polyethylene glycol dimethacrylate (polyethylene glycol dimethacrylate, PEGDMA, n is 4 or 5) represented by the following formula.

Comparative Example 6

The electrolyte of Comparative Example 1 was prepared by adding 5 wt% of polyethylene glycol dimethacrylate (polyethylene glycol dimethacrylate, PEGDMA, n is 8 or 9) represented by the following formula.

Comparative Example 7

An electrolyte was prepared by adding 5% by weight of polyethylene glycol dimethacrylate (PEGDMA, n is 13) represented by the following formula to the electrolyte of Comparative Example 1.

Capacitor Manufacturing

Between two active carbon electrodes, a cellulose separator was interposed and assembled into a pouch cell.

Cells were injected with the electrolytes prepared in Comparative Examples 1 to 7 and Examples 1 and 2, and gelled by heating at 60 ° C. for 18 hours.

Experimental Example 1: ion storage capacity measurement

After discharge to 0 V at a discharge rate of 0.1 A g-1, open circuit voltage (OCV) for 2 hours was measured.

As shown in FIG. 1, in the case of Example 2, it was confirmed that the open circuit voltage was increased in a shorter time than Comparative Example 1, and this is due to the influence of the gel polymer electrolyte around the electrode of Example 2, which further ionizes ions You can see that Through this, it is thought that faster charging and discharging will be possible at high rates, so it is judged that the high rate capacity can be improved.

Experimental Example 2: Measurement of ion conductivity

Cellulose separator was inserted between stainless disks having a diameter of 16 mm, and the electrolyte was injected and impregnated and sealed with a pouch, and then ion conductivity was measured using EIS for each electrolyte.

As shown in FIG. 2, all gel polymer electrolyte compositions compared to Comparative Example 1 can be confirmed to have a poor ionic conductivity. In the case of Comparative Example 2, a slightly inferior appearance was observed in Comparative Example 1, but in the case of Example 2, the inferiority of Comparative Example 2 was confirmed. In Example 1, the ionic conductivity was improved because the monomer used in Example 2 was contained in a molar ratio more than the monomers used in Comparative Example 2 (molar ratio of monomers used = 9: 4). You can see that it looks close. Therefore, through Example 1, it can be confirmed that the effect of improving the high-rate capacity through Example 2 and the effect of improving the ion conductivity through Comparative Example 2 can be simultaneously used.

Experimental Example 3: Measurement of charge and discharge performance for each electrolyte

The prepared cells were subjected to CC (constant current; galvanostatic) charge, CC discharge, and 0 to 3.4 V charge and discharge at a rate of 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 A g ^-1 for each rate at 20 ° C. After performing the cycle experiment five times for each rate, the fifth cycle capacity for each rate was measured and shown in FIG. 3.

As shown in FIG. 3, since Comparative Example 1 and Comparative Example 2 simply implement electrical double-layer capacitance, it can be seen that Comparative Example 1 is similar to or slightly higher than Comparative Example 2 in the overall charge / discharge rate. In Example 2, since the ion storage capacity confirmed in FIG. 1 is higher than that in Comparative Example 1, it can be confirmed that the capacity at a high rate is increased. In the case of Example 1, since both the monomer compositions of Example 2 and Comparative Example 2 were included, the ionic conductivity was slightly improved compared to Example 2, and the high-capacity capacity was also included, so it was confirmed that the capacitance was increased compared to all cells. .

Experimental Example 4: Cycle life evaluation

The prepared cells were charged and discharged 0 to 3.4 V at room temperature at 20 ° C for 5000 cycles with CC-charge and CC-discharge at 3.2 A g ^-1 rate. The charge / discharge cycle capacity was measured and is shown in FIG. 4.

In addition, the capacitance recovery rate is shown in FIG. 5.

Also, the anode / cathode voltage is shown in FIG. 6.

In the case of Comparative Example 1 and Comparative Example 2, it exhibited the lowest lifespan characteristics at 3.4 V charge and discharge. This is interpreted as a deterioration in the lifespan due to the generation of a component that does not recover as a result of conducting a capacitance recovery test of a secondary battery at a low rate. In the case of Example 2 and Example 1, it exhibited excellent life characteristics when charging and discharging 3.4 V, and it was found that the life characteristics of Example 1 were better. This is a phenomenon that appears because the recovery of the capacitance at a low rate is more improved than Comparative Example 1 and Comparative Example 2, and the better the life characteristics of Example 1 than Example 2, the voltage band at the cathode remains stable in Example 1 It seems to be due to the appearance. During the cycle test, the capacitance reduction rate was about 49% in Comparative Example 1, about 25% in Example 2, about 33% in Comparative Example 2, and about 19% in Example 1, indicating that the lifespan reduction rate of Example 1 was the lowest. Can be confirmed.

Experimental Example 5: EIS resistance evaluation

The EIS was measured in the frequency range between 30 mHz and 200 kHz at a amplitude of 10 mV with a 3.4 V charge in the prepared cell before and after the cycle life evaluation at 20 ° C.

7 and 8, as a whole, in the case of Comparative Example 1 and Comparative Example 2, it was confirmed that both the bulk resistance and the interfacial resistance increased significantly before and after the cycle, and that the increase in the interfacial resistance was greater than the increase in the bulk resistance. Can be confirmed. It can be confirmed that the monomer composition used in Example 2 was able to suppress the increase in resistance, and in the case of Example 1, in addition to the performance improvement in Experimental Examples 3 and 4, the increase rate of each resistance component was also maintained to the extent of Example 2. there was.

Experimental Example 6: Measurement of charge and discharge performance for each electrolyte

The prepared cells were tested at a rate of 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 A g-1 for each rate at 20 ° C, and CC (constant current; galvanostatic) charge, CC discharge, 0 to 3.4 V charging and discharging 5 times for each rate Was conducted. The 5th cycle capacity at each rate at the initial 20 ° C was measured and shown in FIGS. 9 and 10.

As shown in FIG. 9, it can be seen that as the content of the additive increases, the amount of the polymer contained in the active material increases, and the effect of increasing the electrolyte resistance is greater than that of the liquid electrolyte, thereby decreasing efficiency.

As shown in FIG. 10, it can be confirmed that as the molecular weight of the additive increases, the number of molecules decreases, and the polymer structure of the gel polymer electrolyte becomes sparse, resulting in weakening of the ability to accommodate the liquid electrolyte, resulting in decreased efficiency.

The present invention is not limited to the above embodiments, but may be manufactured in various different forms, and those skilled in the art to which the present invention pertains have other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that can be implemented as. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (9)

An electrolyte additive comprising a compound represented by the following Chemical Formula 1 and a compound represented by the following Chemical Formula 2;
Acetonitrile solvents; And
Gel polymer electrolyte containing an electrolyte salt.
[Formula 1]

(In the formula (1), R ¹ to R ⁴ each represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 13.)
[Formula 2]

(In Formula 2, R ⁵ represents hydrogen or an alkyl group.
R ⁶ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.) According to claim 1,
The compound represented by Chemical Formula 2 is a gel polymer electrolyte that is a compound represented by Chemical Formula 3 below.
[Formula 3]

(In the formula (3), R ⁷ represents hydrogen or an alkyl group.
R ⁸ is hydrogen, straight-chain or branched alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, halogen atom, haloformyl group, carbonyl group, aldehyde group, carboxyl group, ester group, amide group, cyanic acid group, It represents an isocyanate group, nitrile group, nitro group, sulfonyl group, sulfo group, sulfinyl group, amine, hydroxy group or alkoxy group.
X represents an alkylene group having 1 to 6 carbon atoms.
m represents an integer from 1 to 22.) According to claim 1,
In Formula 1, R ¹ and R ² are each a hydrogen or methyl group, and R ³ and R ⁴ are hydrogen. According to claim 1,
The n is an integer of 1 to 4 gel polymer electrolyte. According to claim 2,
In Formula 3, R ⁷ and R ⁸ are each a hydrogen or methyl group, and X is -CH ₂ -gel polymer electrolyte. According to claim 1,
A gel polymer electrolyte containing 1 to 8% by weight of the electrolyte additive. According to claim 1,
The electrolyte additive is a gel polymer electrolyte in which the weight ratio of the compound represented by Formula 1 and the compound represented by Formula 2 is 1: 1 to 3: 1. An electrochemical capacitor comprising the gel polymer electrolyte according to any one of claims 1 to 7. The method of claim 8,
Anode and cathode;
The gel polymer electrolyte interposed between the positive electrode and the negative electrode, and
An electrochemical capacitor comprising a polymer film formed on the surface of at least one of an anode and a cathode.

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