KR20170113772A - Current collector for Electrochemical energy storage device and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to a current collector for an electrochemical energy storage device for preventing leakage of an electrolyte solution by making a potential of a current collector higher than a potential of a terminal and a method of manufacturing the same, Which is capable of suppressing the leakage of the electrochemical energy storage device, and a manufacturing method thereof. The current collector for an electrochemical energy storage device according to the present invention is characterized in that a film is formed on the outer surface by chemical conversion through a solution containing an organic or inorganic weak acid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collector for an electrochemical energy storage device,

The present invention relates to a current collector for an electrochemical energy storage device, and more particularly, to a current collector for an electrochemical energy storage device for preventing leakage of an electrolytic solution by making a potential of a current collector higher than a potential of a terminal, will be.

In the information age, high-value-added industries that collect and utilize diverse and useful information in real time through various information and communication devices are leading. In order to secure the reliability of such systems, it is recognized that supply of stable energy is an important factor.

As part of securing stable energy, an electrochemical energy storage device, which can convert electrical energy into chemical energy and store it, and convert it into electrical energy when necessary, is used.

Batteries, which are the most common electrochemical energy storage devices, are widely used because they can store a considerable amount of energy in relatively small volumes and weights, and can output moderate power in many applications. However, batteries have a common problem of low storage characteristics and low cycle life regardless of type. This is due to the natural deterioration of the chemical contained in the battery or deterioration due to use. The disadvantage of such a battery is a natural phenomenon, so no alternative is presented.

An electric double-layer capacitor (EDLC) is an energy storage device using an electric double layer formed between an electrode and an electrolyte, unlike a battery using a chemical reaction.

The basic structure of the electric double layer capacitor is composed of an electrode, an electrolyte, a current collector, a separator, and a terminal exposed to the outside in connection with the current collector. A series of electrochemical mechanisms in which a voltage of a bolt is applied to move the ions in the electrolytic solution along the electric field to be adsorbed on the surface of the electrode.

On the other hand, the current collector is divided into a positive current collector and a negative current collector, and accumulates electrons generated by the electrochemical reaction of the active material and transfers the accumulated electrons to the external circuit through the terminal.

Here, since the electric potential of the terminal of the electric double layer capacitor is higher than the electric potential of the current collector, a phenomenon that the internal electrolyte reacts with the terminal and leakage of the internal electrolyte may occur.

Such leakage of the electrolytic solution causes deterioration of electrical characteristics such as lowering of the electrostatic capacity of the electric double layer capacitor, which may shorten the service life.

Korean Patent No. 10-0783736 (Dec. 3, 2007)

Accordingly, an object of the present invention is to provide a current collector for an electrochemical energy storage device and a method of manufacturing the same, which can suppress leakage of an electrolyte generated when the potential of the terminal is higher than the potential of the current collector.

The current collector for an electrochemical energy storage device according to the present invention is characterized in that a film is formed on the outer surface by chemical conversion through a solution containing an organic or inorganic weak acid.

In the current collector for an electrochemical energy storage device according to the present invention, the organic or inorganic weak acid includes at least one of boric acid, phosphoric acid and adipic acid.

In the current collector for an electrochemical energy storage device according to the present invention, the solution is characterized in that an alkali additive is added to the organic or inorganic weak acid.

In the current collector for an electrochemical energy storage device according to the present invention, the acacilli additive may include at least one of ammonia water, cassia soda, borax, ammonium borate, ammonium phosphate and ammonium adipic acid.

The method for manufacturing a current collector for an electrochemical energy storage device according to the present invention includes the steps of forming a coating on a surface of a current collector through a solution containing an organic or inorganic weak acid, And drying the washed collector-formed current collector.

The current collector for an electrochemical energy storage device according to the present invention is formed by forming a film on the outer surface by chemical conversion through a solution containing an organic or inorganic weak acid so that the potential of the current collector is formed to be equal to or higher than the potential of the terminal Thus, leakage of the electrolytic solution, which is generated when the potential of the terminal is higher than the potential of the current collector, can be suppressed.

1 is a perspective view of an electrochemical energy storage device according to an embodiment of the present invention.
2 is an exploded perspective view of an electrochemical energy storage device according to an embodiment of the present invention.
3 is a cross-sectional view of a current collector for an electrochemical energy storage device according to an embodiment of the present invention.
4 is a flowchart illustrating a method of manufacturing a current collector for an electrochemical energy storage device according to an embodiment of the present invention.

In the following description, only parts necessary for understanding the embodiments of the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of an electrochemical energy storage device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of an electrochemical energy storage device according to an embodiment of the present invention, 1 is a cross-sectional view of a current collector for a chemical energy storage device.

1 and 2, an electrochemical energy storage device 100 includes an electrode element 10, an electrode terminal 20, a case 50, a rubber cap 60, and a polymer resin 70.

The electrode element 10 stores electrochemical energy, and converts electrical energy into chemical energy or chemical energy into electrical energy. The electrode element 10 includes an anode 11, a cathode 13, an electrolyte (not shown), and a separator 15.

The positive electrode 11 and the negative electrode 13 include an electrode material made of a slurry provided on both surfaces or one surface of the current collector 90 and the current collector 90.

The current collector 90 accumulates electrons generated by the electrochemical reaction of the active material in the electrode element 10 and transmits the accumulated electrons to an external circuit. The current collector 90 may be made of a single material such as polycarbonate (PC), aluminum, nickel, titanium, copper, gold, silver, platinum or cobalt, or an alloy or a chemical. Examples of the conductive carbon, polyaniline, , Polyphenylene sulfide, and polyphenol. In particular, the cathode active material, the conductive material, and the binder are used as the cathode material and the cathode material made of the slurry.

Here, the current collector 90 according to the embodiment of the present invention may be chemically treated through a solution containing organic or inorganic weak acid to form the coating 80 on the outer surface. Preferably, the coating 80 may be formed on the outer surface of the current collector provided on the cathode.

The organic or inorganic weak acid contained in the solution comprises at least one of boric acid, phosphoric acid and adipic acid.

Here, when the coating film 80 is formed on the current collector 90 with an aqueous solution of a neutral salt by adding an appropriate amount of alkali, the potential of the current collector 90 can be effectively increased.

Therefore, the current collector 90 according to the embodiment of the present invention can form the coating 80 on the surface of the current collector by adding an alkali additive to a solution containing an organic or inorganic weak acid.

Wherein the alkali additive may comprise at least one of ammonia water, cassia soda, borax, ammonium borate, ammonium phosphate, and ammonium adduct.

As the electrode active material, a substance capable of adsorbing or desorbing a cation or anion of a salt in the electrolyte into the current collector 90 may be used. That is, activated carbon may be used as an electrode active material. Porous carbon-based materials having high electrical conductivity, thermal conductivity, low density, suitable corrosion resistance, low coefficient of thermal expansion, and high purity can be used as the electrode active material. For example, an activated carbon powder (ACP), a carbon nano tube (CNT), a graphite, a vapor grown carbon fiber (VGCF), a carbon aerogel, Carbon nano fiber (CNF) produced by carbonizing a polymer such as polyacrylonitrile (PAN) and polyvinylidenefluoride (PVdF) may be used.

The conductive material may be carbon black (CB), acetylene black, ketjen black, graphite, super-p, or the like as a material for imparting conductivity to the electrode .

The binder serves as a bridge for bonding the electrode active material and the conductive material and for binding the electrode active material and the current collector (90). Materials usable as binders include carboxy methyl cellulose (CMC), polyvinylpyrrolidone (PVP), fluorinated polytetrafluoroethylene (PTFE) powder or emulsion, and rubber-based styrene butadiene rubber ( styrene butadiene rubber (SBR), and the like. These materials may be used in a mixture of at least one of these materials.

The CMC maintains the viscosity of the electrode slurry in a state similar to that of the paste and enhances the binding force with the current collector (90). CMC increases the binding force but increases the embrittlement of the electrode material layer after casting the electrode slurry. CMC can be used to obtain the binding force between the current collector and the electrode slurry.

Polyvinylpyrrolidone serves as a dispersant and helps disperse the particles constituting the electrode slurry. Polyvinylpyrrolidone can be substituted if there are other substances that are low in addition and can aid dispersion.

Polytetrafluoroethylene is emulsified in the electrode slurry and melts at the melting point or higher, so that the polymer is held by the polymer like a web. Polytetrafluoroethylene can stably increase the bonding force between particles.

Rubber-based styrene-butadiene rubber protects the surface by coating the surface of the particles.

Additionally, the binder may further comprise polyvinylidene fluoride, carboxymethyl cellulose, hydropropyl methylcellulose, polyvinyl alcohol, and the like.

The electrolytic solution can make the charge generated from the positive electrode and the negative electrode move smoothly, and can be composed of a salt of a cation and an anion as a liquid solvent. For example, hydrochloric acid, sulfuric acid, nitric acid, acetic acid may be used alone or in combination with distilled water by selecting two or more electrolytes. It is also possible to use Li ₂ SO ₄ , Na ₂ SO ₄ , K ₂ SO ₄ , (NH ₄ ) ₂ SO ₄ , LiOH, NaOH, KOH and NH ₄ OH alone or in combination with distilled water have.

As the electrolyte, a cyclic carbonate, a linear carbonate, a lactone, an ether, an ester, a ketone, and / or water may be used.

Examples of the cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of the linear carbonate include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate ), Ethyl methyl carbonate (EMC), and methyl propyl carbonate (MPC). Examples of the lactone are gamma butyrolactone (GBL), and examples of the ether include dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane and the like . Examples of the esters include methyl acetate, ethyl acetate, methyl propionate, methyl pivalate, and the like. The ketones include, but are not limited to, polymethyl vinyl ketone. These solvents may be used alone or in admixture of two or more.

This, as well as the electrolytic solution as Li ^+, Na ^+, K ⁺ or a cation including an alkali metal ion composed of a combination thereof, such as, and _{^{PF 6 -, BF 4 -,}} Cl -, Br -, I-, ClO 4 - , Anions such as ASF ₆ ^- , CH ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N (CF ₃ SO ₂ ) ₂ ^- , C (CF ₂ SO ₂ ) ₃ ^- (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile (AN), dimethoxyethane, diethoxyethane, An organic solvent selected from the group consisting of tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone or a mixture thereof may be used. TEABF ₄ (tetraethylammonium tetrafluoroborate), TEMABF ₄ (triethylmethylammonium tetrafluoroborate), LiClO ₄ (lithium perchlor orate, lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate (LiAsF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ), or a mixture of two or more salts thereof.

The electrolytic solution may be used to impregnate or coat the separation membrane 15.

The separator 15 is positioned between the anode 11 and the cathode 13 and electrically insulates them. The separation membrane 15 is not limited to a specific type, but it is preferable to use a porous separation membrane. For example, a pulp system, a polypropylene system, a polyethylene system, or a polyolefin system porous separation membrane may be used.

The electrode element 10 is formed by laminating a separator 15 on both surfaces of an anode 11, a cathode 13, between an anode 11 and a cathode 13, or between an anode 11 and a cathode 13, do. That is, the electrode element 10 according to the first embodiment of the present invention can be wound and formed into a cylindrical shape.

The electrode element 10 includes a pair of electrode terminals 20 protruding from the upper side of the electrode element 10. The pair of electrode terminals 20 can be divided into a first electrode terminal 30 and a second electrode terminal 40. The pair of electrode terminals 20 are connected to the positive electrode 11 and the negative electrode 12, It connects with power.

The first electrode terminal 30 includes a first connection portion 31 connected to the anode 11, a first electrode tab 35 composed of a first round portion 33 connected to the first connection portion 31, And a first external connection portion 37 welded to the first portion 33. The second electrode terminal 40 includes a second connection portion 41 connected to the cathode 13, a second electrode tab 45 composed of a second round bar portion 43 connected to the second connection portion 41, And a second external connection portion 47 welded to the round bar portion 43.

At this time, the first electrode terminal 30 and the second electrode terminal 40 can be made of one material of aluminum steel or stainless steel, and the surface can be coated with nickel or tin.

The case 50 is formed with an opening portion at the top, and the electrode element 10 is embedded through the opening portion. Not only the electrode elements 10 but also the gas generated in the electrode elements 10 are present in the case 50. The material of the case 50 is aluminum or aluminum alloy which is light in weight, Can be used.

The case 50 includes a fixing portion 51 which is formed by depressing the side surface which is in contact with the rubber cap 60, which will be described later, by an external pressure. The fixing portion 51 is a portion which is inserted through the opening portion of the case 50 and then deformed concavely inward by the external pressure so that the case 50 and the rubber cap 60 ) Are closely contacted to perform primary sealing. Also, after the rubber cap 60 is inserted into the case 50, the case end 53 may be deformed into a hook shape, and the hook shape may be formed so as to be spaced apart from the rubber cap 60.

The case 5 may be formed in a cylindrical shape and the maximum diameter? ₁ is 18.1 mm 占 0.1, the diameter? ₂ of the portion where the fixing portion 51 is formed is 16.3 mm 占 0.1, (H ₁ ) is 40.7 mm ± 0.05, and the height (H ₂ ) from the fixing portion 51 to the upper portion of the case is 3.8 mm ± 0.1.

However, the case 50 is not limited to a cylindrical shape but may be formed in a shape corresponding to the shape of the electrode element 10. [ In other words, when the electrode element 10 is cylindrical, the case 50 is also cylindrical, and when the electrode element 10 is polygonal, the case 50 may also be polygonal. However, the technical idea of the present invention is not limited to this, and when the electrode element 10 is cylindrical, the case 50 may be polygonal, and when the electrode element 10 is polygonal, May be cylindrical.

The rubber cap (60) is coupled inside the upper portion of the opening portion to seal the case (20). That is, the rubber cap 60 is sealed in the inside of the case 20, so that the inside and the outside of the electrode element 10 can be cut off.

The rubber cap 60 may be made of an elastic rubber material. As the rubber material, for example, olefinic synthetic rubbers such as ethylene propylene copolymer (EPT) and ethylene propylene diene copolymer (EPDM), silicone rubber, fluorine rubber, butyl rubber and the like can be used.

The rubber cap 60 is formed with a first through hole 61 and a second through hole 63 so as to be fitted to the first electrode terminal 30 and the second electrode terminal 40, respectively. That is, the rubber cap 60 may be installed on the upper portion of the electrode element 10 through the first through hole 61 and the second through hole 63. Therefore, the rubber cap 60 and the electrode element 10 can be installed at a distance of 0.4 mm to 10 mm. Thus, the rubber cap 60 can suppress the generation of foreign matter on the surface.

That is, since the electrochemical energy storage device 100 is installed with a distance between the rubber cap 60 and the electrode element 10, even if the electrochemical energy storage device 100 is used for a long time, no foreign matter is generated, and the lifetime can be increased.

As described above, the electrochemical energy storage device 100 is installed at a distance of 0.4 mm to 10 mm between the rubber cap 60 and the electrode element 10. If the spacing distance is shorter than 0.4 mm, When the chemical energy storage device 100 is used for a long time, foreign matter is generated on the surface of the rubber cap 60 or the lifetime thereof is shortened quickly. If the separation distance is further than 10 mm, the energy density of the electrochemical energy storage device 100 is lowered do.

The polymer resin 70 is formed so that the opening end 53 is locked on the upper surface of the rubber cap 60. Therefore, the polymer resin 70 can prevent the liquid leakage phenomenon in which the electrolyte leaks to the outside by performing the secondary sealing of the case 50. Particularly, the polymer resin 70 may be formed so as to cover the open end 53 and finish the case end 53 at the same time.

The polymer resin 70 may be made of a polymer resin having excellent mechanical properties and heat resistance, and may preferably be made of an epoxy resin.

An epoxy resin is a thermosetting resin produced by polymerization of a dendritic substance and an epoxy group having an epoxy group in a molecule and has excellent mechanical properties such as bending strength and hardness and has no generation of volatile substances and no shrinkage in volume at the time of curing, And has a large adhesive force on the surface.

Particularly, the polymer resin 70 may be at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, hydrogenated bisphenol A type epoxy resin, BPA-novolak-type epoxy resin, cycloaliphatic epoxy resin, or a mixture thereof.

Hereinafter, a method of manufacturing a current collector for an electrochemical energy storage device according to an embodiment of the present invention will be described.

4 is a flowchart illustrating a method of manufacturing a current collector for an electrochemical energy storage device according to an embodiment of the present invention.

Referring to FIG. 4, a current collector manufacturing method according to an embodiment of the present invention can form a coating on a surface of a current collector through a solution containing organic or inorganic weak acid in step S10.

The organic or inorganic weak acid contained in the solution comprises at least one of boric acid, phosphoric acid and adipic acid.

Here, when a suitable amount of alkali is added to form a film on the positive electrode current collector and the negative electrode current collector with an aqueous solution of a neutral salt, the potential of the current collector can be effectively increased.

Therefore, an alkali additive may be added to a solution containing an organic or inorganic weak acid to form a coating on the surface of the current collector.

Wherein the alkali additive may comprise at least one of ammonia water, cassia soda, borax, ammonium borate, ammonium phosphate, and ammonium adduct.

Next, in step S20, the surface of the current collector on which the film is formed can be cleaned.

The current collectors for the electrochemical energy storage device according to the embodiment of the present invention can be manufactured by drying the coated current collector which has been cleaned in the step S30.

As described above, the current collector for an electrochemical energy storage device according to an embodiment of the present invention is formed by forming a film on the outer surface by chemical conversion treatment through a solution containing an organic or inorganic weak acid so that the potential of the current collector is compared with the potential of the terminal So that leakage phenomenon of the electrolyte generated when the potential of the terminal is higher than the potential of the current collector can be suppressed.

It should be noted that the embodiments disclosed in the drawings are merely examples of specific examples for the purpose of understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: electrode element 11: anode
13: cathode 15: separator
20: electrode terminal 30: first terminal
31: first connecting portion 33: first round bar
35: first electrode tab 37: first external connection
40: second terminal 41: second connection part
43: second round bar 45: second electrode tab
47: second external connection part 50: case
51: Fixed portion 53: Case end
60: Rubber cap 61: First through hole
63: second through hole 70: polymer resin
80: Coating 90: Current collector
100: Electrochemical energy storage device

Claims (5)

Wherein the film is chemically treated through a solution containing an organic or inorganic weak acid to form a coating on the outer surface. The method according to claim 1,
Wherein the organic or inorganic weak acid comprises at least one of boric acid, phosphoric acid, and adipic acid. 3. The method of claim 2,
Wherein the solution is an organic or inorganic weak acid to which an alkali additive is added. The method of claim 3,
Wherein the eucalyptus additive comprises at least one of ammonia water, cassia soda, borax, ammonium borate, ammonium phosphate, and ammonium adapic acid. Forming a coating on the surface of the current collector through a solution containing organic or inorganic weak acids;
Cleaning the surface of the current collector on which the film is formed;
Drying the cleaned coated current collector;
Wherein the collector is made of a material selected from the group consisting of silicon carbide and silicon carbide.

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