KR20170059205A - Manufacturing method of supercapacitor for improved thermal stability, and supercapacitor made by the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a capacitor with improved thermal stability, and a capacitor manufactured thereby. More specifically, the present invention relates to a method for manufacturing a capacitor which manufactures a capacitor by curing after preliminarily impregnating an electrode and a separator in an electrolyte composite, and a capacitor manufactured thereby.

Description

Technical Field [0001] The present invention relates to a method of manufacturing a capacitor having improved thermal stability and a capacitor manufactured thereby,

The present invention relates to a method of manufacturing a capacitor having improved thermal stability and a capacitor manufactured thereby. More particularly, the present invention relates to a capacitor manufactured by impregnating an electrode and a separator with an electrolyte composition in advance and then curing the electrode and separator. Thereby manufacturing a capacitor. The present invention also relates to a capacitor manufactured by the method.

Recently, the application of energy storage technology to cell phones, camcorders, notebook PCs and electric vehicles has expanded, and efforts for battery research and development are becoming more concrete.

Electrochemical devices have attracted the greatest attention in this respect, and in particular, with the recent trend toward miniaturization and weight reduction of electronic devices, development of electrochemical devices including lithium secondary batteries and capacitors capable of charging and discharging at a small size, It is becoming the focus.

An electrochemical device including a lithium secondary battery and a capacitor can be generally manufactured by using an anode and a cathode including an electrode active material capable of intercalating / deintercalating lithium ions, and an electrolyte that is a medium for transferring lithium ions.

Conventionally, an ion conductive organic liquid electrolyte in which a salt is dissolved in a liquid electrolyte, particularly a non-aqueous organic solvent, has been mainly used as the electrolyte. However, such a liquid electrolyte may leak during operation, and there is a problem that ignition, explosion, and the like are caused by the high flammability of the non-aqueous organic solvent to be used. Further, the liquid electrolyte decomposes the carbonate organic solvent during charging and discharging of the lithium secondary battery, or generates a side reaction with the electrode to generate gas inside the battery. This reaction accelerates further at high temperature storage, so the amount of gas generated increases. Such continuously generated gas causes an increase in the internal pressure of the battery, which not only causes deformation of the cell such as expanding the thickness of the cell but also causes a local difference in the adhesion at the electrode surface in the cell, Causing problems that do not occur equally.

In order to overcome the safety problem of the liquid electrolyte in recent years, there has been proposed a method of using a gel polymer electrolyte free from leakage and the like. The gel polymer electrolyte is prepared by impregnating a polymer matrix formed by a polymerization reaction of a polymerizable monomer and a polymerization initiator with an electrolyte solution containing an electrolyte salt and a non-aqueous organic solvent, and then gelling the polymer matrix.

The lithium secondary battery including the gel polymer electrolyte can be manufactured in the pouch type shown in FIG. 1, an electrolyte composition including a salt, a solvent, a monomer, and an initiator is first prepared, and an electrode, a separator, and a casing are prepared to assemble the battery. An electrolyte was injected into the pouch-type battery cell, the electrolyte was impregnated under reduced pressure, cured after sealing, degassed, and vacuum sealed to prepare a battery.

However, in the conventional pouch-type gel polymer battery manufacturing process, an initiator such as AIBN or BPO is used and after curing, the initiator is decomposed in the curing process to generate N2 or CO2 gas, Which deteriorates the electrochemical characteristics.

On the other hand, in the method of manufacturing the coin cell type using the liquid electrolyte shown in FIG. 2, the battery is injected, injected, and impregnated with a reduced pressure. Unlike the pouch type, there is no separate degassing after curing, There is a problem that the pressure becomes high and the electrolytic solution leaks and the battery performance deteriorates.

In order to solve the problems of the prior art as described above, in the process of applying the gel polymer electrolyte, the main components of the capacitor including the electrode and the separator are impregnated with the electrolyte composition in advance, cured and then sealed It is another object of the present invention to provide a method of manufacturing a new capacitor which can prevent deterioration of capacitor performance due to a low molecular compound such as a gas which is generated after curing but can not be discharged to the outside.

The present invention also aims to provide a capacitor manufactured by the manufacturing method of the present invention.

The present invention has been made to solve the above problems

Preparing an electrolyte composition comprising a monomer, an initiator, an electrolyte salt, and an organic solvent;

Preparing an electrode and a separator;

Inserting the electrode and the separator into a casing;

Injecting the electrolyte composition into the exterior material, and impregnating the electrode and separator inserted into the exterior material;

Curing the electrode and separator impregnated in the electrolyte composition;

Sealing the electrolyte-impregnated and cured electrode and the exterior material into which the separator is inserted; And a method of manufacturing the capacitor.

According to the present invention Capacitor  Produce In the method , Said electrolyte composition comprising: i) by polymerization or crosslinking; Gel-like  A molecular weight ranging from 50 to 5000 Acrylate series  Characterized by comprising a monomer do.

remind Acrylate series  As the monomer, Tetraethylene  Glycol Diacrylate tetraethylene glycol 다경화 ), Poly Ethylene glycol Diacrylate ( Poly ethylene  glycol 다경화 , Molecular weight 50 to 5,000), 1,4- Butanediol Diacrylate (1,4-butanediol 다경화 ), 1,6- Hexanediol Diacrylate (1,6- hexanediol  diacrylate), Trimethylolpropane Triacrylate ( trimethylolpropane  triacrylate), Trimethylol  Propane Ethoxylate Triacrylate trimethylolpropane ethoxylate 트리acrylate ), Trimethylol  Propane Propoxylate triacrylate trimethylolpropane propoxylate 트리acrylate ), Ditrimethylolpropane Tetraacrylate ( ditrimethylolpropane 테트라acrylate ), Pentaerythritol 테트라acrylate ), Pentaerythritol Ethoxylate Tetraacrylate ( pentaerythritol ethoxylate 테트라acrylate ), Dipentaerythritol Pentaacrylate ( dipentaerythritol pentaacrylate ), Dipentaerythritol Hexaacrylate (dipentaerythritol hexaacrylate ), Glycidyl Methacrylate (glycidyl 메록acrylate ), Polyethylene glycol  Methyl ether Methacrylate (ethylene glycol) methyl ether 메록acrylate  (Molecular weight: 50 to 5000). However, the present invention is not limited thereto. These compounds may be used singly or in combination of two or more.

The monomer may be included in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the mixture of the electrolyte solvent and the electrolyte salt. If the amount of the monomer is more than 20 parts by weight, gelation occurs too quickly or becomes too dense during the injection of the composition for a gel polymer electrolyte into the battery, resulting in a gel having a high resistance. Conversely, if the monomer is less than 0.01 part by weight, The problem may arise.

Initiator

In the method for producing a capacitor according to the present invention, the electrolyte composition includes a peroxide type compound represented by the following formula (1) or an initiator of the azo type compound represented by the formula (2).

[Chemical Formula 1]

In the above formula (1), R represents an alkyl, aryl-based functional group, or BENZOYL PEROXIDE or Di (4-methylbenzoyl) peroxide.

(2)

In Formula 2, R ₁ and R ₂ represent an alkyl group, 2,2-azobis (2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4 dimethylvaleronitrile) and the like.

In the method of manufacturing a capacitor according to the present invention, it is possible to further include an electrolyte salt in the electrolyte composition. In the method for producing a capacitor according to the present invention, it is preferable that the electrolyte salt includes at least one electrolyte salt selected from the group consisting of a quaternary ammonium salt or a lithium salt. Any quaternary ammonium salt or lithium salt can be used as long as it is an electrolyte capable of generating quaternary ammonium ions or lithium ions. It is more preferable to use at least one selected from the group consisting of quaternary ammonium salts and lithium salts. In particular, ethyl trimethyl ammonium BF _4, diethyl-dimethyl ammonium BF _4, triethyl methyl ammonium BF _4, tetraethylammonium BF _4, spiro - (N, N ') - bipyridinium Raleigh pyridinium BF _4, ethyl trimethyl ammonium PF _6, D dimethyl ammonium PF _6, triethyl methyl ammonium PF _6, tetraethyl ammonium PF _6, spiro - (N, N ') - bipyridinium Raleigh pyridinium PF _6, tetramethyl ammonium bis (oxalate reyito) borate, ethyl trimethyl ammonium bis (oxalate (Oxalate) borate, tetraethylammonium bis (oxalate) borate, spiro- (N, N ') - bipyrrolidinium bis (oxalate) borate, diethyldimethylammonium bis Oxalate) borate, tetramethylammonium difluoroarsalateborate, ethyltrimethylammonium difluoroarsalateborate, diethyldimethylammonium difluoroarsalateborate, triethylmethylammonium difluoro Oxalate reyito as a oxalate reyito borate, tetraethylammonium di-tetrafluoroborate, spiro - (N, N ') - bipyridinium pyrrolidinyl nyumdi fluoro-oxalate reyito borate, LiBF _4, LiPF _6, lithium bis (oxalate reyito) borate, lithium di Fluorooxalate borate, methylethyl pyrrolidinium tetrafluoroborate and the like are preferable.

In the method for producing a capacitor according to the present invention, examples of the organic solvent for the electrolyte composition include ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, dimethyl carbonate, Diethyl carbonate, ethyl isopropyl sulfone, ethyl methyl sulfone and ethyl isobutyl sulfone, sulfolane, 3-methyl sulfolane,? -Butyrolactone, acetonitrile, 1,2-dimethoxy But are not limited to, ethane, N-methylpyrrolidone, N-methylformamide, dimethylformamide, N-methylacetamide, dimethylsulfoxide, dimethylsulfite, tetrahydrofuran, 2-methyltetrahydrofuran, , Nitromethane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, water or a mixture thereof.

In the method of manufacturing a capacitor according to the present invention, the electrode may be manufactured by a conventional method known in the art. For example, a slurry is prepared by mixing and stirring a solvent, an optional binder, a conductive material, and a dispersing material in an electrode active material, and then applying (coating) the electrode to a current collector of a metal material, have.

In the method of manufacturing a capacitor according to the present invention, the electrolyte composition is injected into the casing, and in the step of impregnating the electrodes and the separator inserted in the casing, impregnation is carried out at a room temperature under a reduced pressure impregnation process. It is preferable to adjust the decompression degree to -60 to -90 kPa and the impregnation time to 2 to 30 minutes depending on the boiling point of the solvent.

In the production method of a capacitor according to the present invention, an electrode inserted in the casing, in the step of impregnating the membrane and the casing needs to have oxygen and moisture barrier in the air because they are not sealed, in a N ₂ or Ar atmosphere for this purpose It needs to be done.

In the method of manufacturing a capacitor according to the present invention, it is preferable that heat and curing be performed in the step of curing the electrode and the separation membrane impregnated in the electrolyte composition. The curing temperature is preferably in the range of 50 to 120 ° C. When the temperature is lower than 50 ° C, curing takes a long time, and when the temperature is higher than 120 ° C, the solvent is decomposed.

In the production method of a capacitor according to the present invention, in the step of ring curing the said electrodes and the separator impregnated with the electrolyte composition and packaging material have to oxygen, water barrier in the air because they are not sealed, N ₂ For this, and It is necessary to be performed in an Ar atmosphere.

In the method of manufacturing a capacitor according to the present invention, a capacitor is prepared by impregnating an electrolyte composition with the electrode and separator in advance, followed by performing a curing process and then sealing the exterior material. Therefore, when the exterior material is subjected to a curing process after sealing, And the like are not left in the produced cell, and the liquid electrolyte component is trapped in the structure, thereby making it possible to manufacture a capacitor having improved high-temperature performance.

1 shows a process for producing a secondary cell to which a gel polymer electrolyte of a conventional pouch type is applied.
2 shows a process for manufacturing a conventional coin type capacitor.
3 shows a photograph of a gel polymer electrolyte prepared according to one embodiment of the present invention.
4 shows leakage test results for the capacitor manufactured in one embodiment of the present invention and a comparative example.
FIG. 5 shows the electrochemical characteristics of the capacitor fabricated according to one embodiment of the present invention and the comparative example.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples.

< Example  1> Capacitor  Produce

As an example, poly (ethylene glycol) methyl ether methacrylate (PEGMEM, Mw = 1100) as a monomer was added to the basic electrolyte of 2.0 M SBPBF ₄ (spiro- (1,1 ') - bipyrrolidium tetrafluoroborate) / sulfolane in 5, And 2 parts by weight of azobisisobutyronitrile (AIBN) as an initiator were added to prepare 3.30 g of a gel polymer electrolyte composition.

A positive electrode and a negative electrode were constituted by a general activated carbon symmetric electrode and attached to a casing, and a separator was interposed therebetween, and then impregnated into the composition for gel polymer electrolyte prepared above.

Thereafter, the positive electrode, the negative electrode and the separator impregnated in the electrolyte solution were subjected to a curing process under a heating condition of 60 ° C for 4 hours, and then the casing was sealed to manufacture a capacitor.

< Comparative Example  1> Capacitor  Produce

As a comparative example, a pregel composition for a gel polymer electrolyte having the same conditions as those in Example 1 was prepared, and then a positive electrode and a negative electrode were formed using a general activated carbon symmetric electrode without pre-curing the electrode and the separator, And the separator was inserted therebetween. The electrolyte composition was poured into a casing, sealed, and then subjected to a curing process under heating conditions at 60 DEG C for 4 hours to prepare a capacitor.

FIG. 3 shows a gel polymer electrolyte in which a composition containing 15% by weight of a monomer unit in the pregel composition prepared in Comparative Example 1 was separately cured in a vial.

Figure 3 (a) shows after curing, showing that the N ₂ gas generated by the decomposition of the initiator during the curing process is trapped within the gel polymer to form bubbles. Fig. 3 (b) shows the vial lid in the state of Fig. 3 (a) being opened.

< Comparative Example  2> Capacitor  Produce

As a comparative example, an electrolyte composition of 2.0 M SBPBF ₄ (spiro- (1,1 ') - bipyrrolidium tetrafluoroborate) / sulfolane was prepared.

The positive electrode and the negative electrode are formed of a conventional activated carbon symmetric electrode and are then attached to the casing and the separator is interposed therebetween. Thereafter, the electrolyte composition is impregnated with the prepared electrolyte composition, and the casing is sealed to form a capacitor Respectively.

< Experimental Example  1> Evaluation of electrochemical characteristics

The ESR of the cells prepared in Example 1, Comparative Example 1 and Comparative Example 2 was measured using a resistance meter (AC 1.0 kHz). The charging of the cell was carried out at a constant current of 100 C to 3.3 V, and then the charging voltage was maintained for 30 minutes. Then, the capacitance was measured by discharging to 0 V at a constant current of 10 C, and the capacitance was measured.

FIG. 4A is a graph showing Capacitance, and FIG. 4B is a graph showing ESR. In FIG. 4A, the capacitances of Comparative Examples 1 and 1 are reduced compared to Comparative Example 2. FIG. In Comparative Example 1, as the content of the monomers increases, the capacitance decreases, whereas the Example 1 maintains the same level.

In FIG. 4B, the ESRs of Comparative Example 1 and Example 1 are increased as compared to Comparative Example 2. It can be seen that the ESR increase of Example 1 is smaller than that of the ESR increases with the increase of the monomer content of Comparative Example 1. [

< Experimental Example  2> Leak  Test

In order to compare the leakages of the capacitors manufactured in Example 1, Comparative Example 1 and Comparative Example 2, they were allowed to stand for a certain period under the condition of 3.3 V in an environment of 50 ° C. and relative humidity (RH) of 95% And the results are shown in Fig.

As shown in FIG. 5, the leakage incidence rate in the cell of Example 1 of the present invention, which was previously impregnated with the electrolyte composition, was lower than that of the cell of Comparative Example 1 using an electrolyte composition but without impregnation.

Claims (8)

Preparing an electrolyte composition comprising a monomer, an initiator, an electrolyte salt, and an organic solvent;
Preparing an electrode and a separator;
Inserting the electrode and the separator into a casing;
Injecting the electrolyte composition into the exterior material, and impregnating the electrode and separator inserted into the exterior material;
Curing the electrode and separator impregnated in the electrolyte composition;
Sealing the electrolyte-impregnated and cured electrode and the exterior material into which the separator is inserted; &Lt; / RTI &gt;
The method according to claim 1,
Wherein the monomer is an acrylate-based monomer having a molecular weight ranging from 50 to 5,000
The method according to claim 1,
Wherein the initiator is represented by the following Chemical Formula 1 or Chemical Formula 2:
[Chemical Formula 1]

In the above formula (1), R represents an alkyl or aryl-based functional group.

(2)

In Formula 2, R ₁ and R ₂ represent an alkyl group.
The method according to claim 1,
Wherein the electrolyte composition further comprises an electrolyte salt selected from the group consisting of a quaternary ammonium salt or a lithium salt.
The method according to claim 1,
Wherein the step of injecting the electrolyte composition into the exterior material and impregnating the electrode and the separation membrane inserted in the exterior material is performed in an inert gas atmosphere containing nitrogen or argon
The method according to claim 1,
Wherein the step of impregnating the electrodes and the separator inserted into the casing comprises injecting the electrolyte composition into the casing and adjusting the degree of decompression to -60 to -90 kPa and the duration of the impregnation to 2 to 30 minutes. &Lt; / RTI &
The method according to claim 1,
Wherein the step of curing the electrode and the separation membrane impregnated in the electrolyte composition is performed in an inert gas atmosphere containing nitrogen or argon
The method according to claim 1,
Wherein the curing of the electrode and the separation membrane impregnated in the electrolyte composition is performed at a temperature of 50 to 120 ° C.

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