KR100486917B1 - Electric storage device and method for manufacturing the same - Google Patents

Abstract

An electrical energy storage device having a polarizing electrode having a large capacitance and a low resistance, and a method of manufacturing the same are disclosed. The activated carbon and the conductive carbon powder are washed, the washed powder is dried and the dried powder is mixed to form a first mixture. The second mixture is mixed with a binder including water-soluble chitosan, a thermosetting resin, a polyvinylidone-styrene copolymer, polytetrafluoroethylene, and the like to form a second mixture, and then the second mixture is formed on a current collector. To form an electrode. The electrode having a high density can be manufactured by greatly improving the binding force between the active materials and the binding force between the active material and the current collector, and the electrochemical stability of the electrode is remarkably improved, thus bringing large capacitance and long-term electrochemical stability. Electric energy storage devices suitable for electric vehicles, unmanned controlled airplanes or uninterruptible power supplies that require large capacity can be manufactured.

Description

Electric energy storage device and method for manufacturing the same

The present invention relates to a method for manufacturing an electrical energy storage device, and more particularly, to a method for manufacturing an electrical energy storage device such as an electric double layer capacitor having a polarization electrode having a large electrode density and a low resistance. will be.

Electrical energy storage devices, such as capacitors or capacitors, are generally classified into electrostatic capacitors, electrolytic capacitors, and electrochemical capacitors.

Electrostatic capacitors include ceramic capacitors, glass capacitors, mica capacitors, and the like, and most of these capacitors have a capacitance of about 1.0 to 10 ㎌.

Meanwhile, electrochemical capacitors, also called super capacitors, include electric double layer capacitors (EDLC) and redox or pseudo capacitors. Capacitance can be secured from about 1 mF to about 3000F.

In addition, aluminum (Al) electrolytic capacitors or tantalum (Ta) electrolytic capacitors are known as electrolytic capacitors, and such electrolytic capacitors are known to have a large capacitance up to about 100 times as compared to electrostatic capacitors.

In an electric double layer capacitor (EDLC), generally, activated carbon in powder form is mixed with carbon black, which is a conductive material, and then the mixture is attached to a current collector using a binder to form an electrode. Will be used. As a binder for forming an electrode, polysaccharide-based and fluorine-based binders are widely used. The binder may be classified into a water-soluble binder and an organic binder according to a solvent for dissolving the binder, and a process for manufacturing an electrode according to the type of binder. You will also see a difference.

The manufacturing method of such an electric double layer capacitor is disclosed in Korean Patent Laid-Open Publication No. 2002-62193 (name of the invention; battery active material mixture powder, battery electrode composition, secondary battery electrode, secondary battery, carbon material mixture powder for electric double layer capacitor, polarizable electrode) Compositions, polarizable electrodes and electric double layer capacitors, Korean Patent No. 334241 (name of the invention; electric double layer capacitors and a method of manufacturing the same), Korean Patent No. 309634 (name of the invention; electric double layer capacitors) and the like. .

Recently, in order to lower the resistance of an electrode of an electric double layer capacitor (EDLC) and at the same time improve the capacitance of the electric double layer capacitor, a method of manufacturing a polarized electrode by forming a current collector made of metal on carbon fiber or activated carbon fiber, carbon A method of manufacturing an electrode by pressing a paste onto a conductive rubber or a metal current collector, a method of applying a slurry containing activated carbon powder to a metal current collector, and the like have been developed.

However, in the case of lowering the electrical resistance of the electrode by applying a metal such as aluminum onto the carbon fiber or the activated carbon fiber by the plasma spray method, the density of the electrode of the electric double layer capacitor is reduced, and the manufacturing cost is increased. There is a drawback to this.

In addition, when the electrode of the electric double layer capacitor is manufactured using activated carbon, since the electrode is manufactured in the form of a paste or a slurry using a fluorine-based binder, the electrode can be increased in density, whereas the electrode is thick. There is a problem in that limitations are encountered in reducing the internal resistance of the electrode.

Accordingly, one object of the present invention is to provide an electric energy storage device having a polarization electrode exhibiting high density and low resistance applicable to an electric energy storage device such as an electric double layer capacitor suitable for an electric vehicle or an uninterruptible power supply or the like requiring a large capacity, and The manufacturing method is provided.

It is another object of the present invention to provide an electrical energy storage device such as an electric double layer capacitor and a method of manufacturing the same, which can be provided with a high-density and low-resistance polarization electrode to realize improved capacitance and electrochemical stability for a long time.

In order to achieve the above objects of the present invention, according to the present invention, there is provided an electrode comprising a mixture comprising activated carbon and conductive carbon, and a binder comprising a water-soluble chitosan for binding the mixture onto a current collector. An electrical energy storage device is provided.

According to one embodiment of the invention, the content of the water-soluble chitosan in the binder is about 3 to 10 parts by weight based on the mixture. At this time, the water-soluble chitosan has a molecular weight of about 5,000 to 10,000.

According to another embodiment of the present invention, about 3 to 7 parts by weight of the thermosetting resin is further added to the binder. In this case, any one selected from the group consisting of polyurethane resins, melamine resins, polyester resins and epoxy resins is used as the thermosetting resin.

According to another embodiment of the present invention, about 1 to 5 parts by weight of the polyvinylidone-styrene copolymer and polytetrafluoroethylene are further added to the binder. In this case, the binder further comprises about 1 to 3 parts by weight of alcohol based on the mixture.

In addition, according to the present invention to achieve the above object of the present invention, the step of washing the activated carbon and conductive carbon powder, drying the washed powder, mixing the dried powder to form a first mixture Electrical energy storage device comprising the steps of: mixing a binder comprising water-soluble chitosan and water with the first mixture to form a second mixture, and applying the second mixture onto a current collector to form an electrode A method for producing is provided. At this time, the content of the activated carbon and the conductive carbon in the first mixture is about 8: 2.

Preferably, the activated carbon and the conductive carbon powder are washed with a solvent containing acetone, and the washed powder is dried at a temperature of 160 to 180 ° C. for about 0.5 to 1.5 hours and then pulverized with a ball mill or the like.

According to the present invention, a binder containing water-soluble chitosan, water-soluble chitosan and thermosetting resin, or water-soluble chitosan, thermosetting resin, alcohol, polyvinylidone-styrene copolymer, polytetrafluoroethylene, etc. may be used as a solvent containing acetone. Slurry having various viscosities can be prepared because it is mixed with the washed activated carbon and conductor carbon powder to form a mixture in the form of a slurry.

In addition, by using the binder having the above-described composition, the binding force between the active materials and the binding force between the active material and the current collector can be greatly improved to prepare an electrode having a high density of about 0.7 to 10 g / cc, and the electrochemical Phosphorus stability is also remarkably improved. Moreover, since the resistance of the electrode is also very small compared with the prior art, it is possible to manufacture an electric energy storage device having a large capacitance and a long electrochemical stability from an electrode showing high density and low resistance.

Hereinafter, the manufacturing method of the electrical energy storage device according to the present invention will be described in detail.

According to the present invention, first, the activated carbon and the conductive carbon powder are prepared, and then the activated carbon and the conductive carbon powder are washed with a solvent containing acetone. Through this washing process, impurities such as carbon monoxide (CO) and carbon dioxide (CO ₂ ) generated on the surface of the activated carbon and the conductive carbon powder are removed during the preparation of the activated carbon and the conductive carbon powder. Table 1 below shows the results of washing activated carbon and conductive carbon powder with a solvent containing acetone according to the present invention.

           ＼ Category Characteristics Density of Electrodes Performing Cleaning Process Electrode Density After Cleaning Process Density (g / cc) 0.48 0.57

As shown in Table 1, when the cleaning process is performed on the activated carbon and the conductive carbon powder, the density of the electrode is increased by about 20% compared with the case where the cleaning process is not performed.

In addition, when washing the activated carbon and the conductive carbon powder with a solvent containing acetone, the activated carbon and the conductive carbon powder are separated from the impurities while acetone used as the solvent is volatilized and a density difference occurs between the carbon powder and the impurities.

By performing the process of washing with a solvent containing acetone as described above, it is possible to completely remove impurities from the activated carbon and the conductive carbon powder, as well as to increase the packing amount of the activated carbon and the conductive carbon.

Subsequently, the washed activated carbon and the conductive carbon powder are added to the dryer, and then the temperature in the dryer is maintained at about 160 to 180 ° C., preferably at about 170 ° C., for about 0.5 to 1.5 hours. Preferably, the activated carbon and conductive carbon powder are dried for about 1 hour.

Subsequently, about 3-10 parts by weight of water-soluble chitosan is added to the mixture of dried activated carbon and conductive carbon powder, or about 3-10 parts by weight of water-soluble chitosan and heat is added to the mixture of activated carbon and conductive carbon powder. About 3 to 7 parts by weight of a thermosetting resin is added to prepare a binder. In this case, any one selected from the group consisting of melamine resin, polyester resin, epoxy resin and polyurethane resin is used as the thermosetting resin.

Also, about 3 to 10 parts by weight of water-soluble chitosan, about 3 to 7 parts by weight of a thermosetting resin, and about 1 to 5 parts by weight of a polyvinyllydone-strene copolymer in a mixture of dried activated carbon and conductive carbon powder And about 1 to 5 parts by weight of polytetrafluoroethylene (polytetrafluroethylene) is added to prepare a binder.

Hereinafter, the method for preparing the binder according to the present invention will be described in detail.

According to an embodiment of the present invention, in order to prepare a binder, the dried activated carbon and conductive carbon powder are pulverized using a ball mill or the like, and then the activated carbon powder and the conductive carbon powder are about 8: 2 Mix in proportion to form a first mixture. The binder is added by adding about 3 to 10 parts by weight, preferably about 5 to 8 parts by weight of a water-soluble chitosan having a molecular weight of about 5,000 to 15,000, preferably about 10,000, based on the first mixture composed of activated carbon and conductive carbon powder. To prepare.

In one embodiment of the present invention, during mixing of the first mixture and the binder, the water-soluble chitosan in the binder plays a very important role in forming the paste into a slurry while being dissolved in water.

Therefore, when the specific surface area of the activated carbon powder is increased, the amount of water-soluble chitosan should be controlled by the molecular weight of the water-soluble chitosan, rather than the state of the slurry. That is, when using the activated carbon powder which has a larger specific surface area, it is preferable to use what has a molecular weight larger than water-soluble chitosan. However, when the amount of the water-soluble chitosan is added too much, since the water-soluble chitosan may surround the surface of the activated carbon powder, it has a detrimental effect on the electrode. Adjustment is required.

According to another embodiment of the present invention, the dried activated carbon and conductive carbon powder is pulverized, the activated carbon powder and the conductive carbon powder are mixed at a ratio of about 8: 2 to form a first mixture, and then the first mixture The binder is prepared by adding about 3 to 10 parts by weight of water-soluble chitosan and about 3 to 7 parts by weight of polyurethane, preferably about 5 parts by weight, as the thermosetting resin. In this embodiment, when a binder is prepared by adding a thermosetting resin to the water-soluble chitosan, an electrode having a very high density can be obtained as described later.

In another embodiment of the present invention, since the binder is prepared by adding a thermosetting resin such as polyurethane resin, melamine resin, polyester resin, epoxy resin, etc., the binder increases the binding force between the active materials constituting the electrode and at the same time The bond between the field and the current collector is also greatly increased.

When the electrode is manufactured through a pressing process at a temperature of about 50 to 150 ° C., preferably about 100 ° C., using a binder having the above-described composition, the density of the electrode is remarkably improved. On the other hand, since the ductility of the electrode is lowered, it is difficult to wind the electrode in a separator or the like.

Further, according to another embodiment of the present invention, the activated carbon powder and the conductive carbon powder are mixed at a ratio of about 8: 2 to form a first mixture, and then about 3 to 10 weight of water-soluble chitosan based on the first mixture. Parts, about 3 to 7 parts by weight of polyurethane, about 1 to 3 parts by weight of alcohol, preferably about 2 parts by weight, about 1 to 5 parts by weight of polyvinylidene-styrene copolymer, preferably Is added in an amount of about 2 to 4 parts by weight, and about 1 to 5 parts by weight of polytetrafluoroethylene, preferably about 2 to 4 parts by weight, to prepare a binder.

In another embodiment of the present invention, when the alcohol is added to prepare the binder, the alcohol serves to smoothly disperse the polyvinylidone-styrene copolymer and the polytetrafluoroethylene in the binder. However, if the addition amount of alcohol is too large, it should be noted that the binder does not play a role properly.

In addition to the water-soluble chitosan and the thermosetting resin to the binder, when the polyvinylidene-styrene copolymer and polytetrafluoroethylene are added, the electrode is pressed at a temperature of about 100 ° C. because the electrode exhibits a high density and excellent ductility. Even during the preparation, the ductility of the electrode does not decrease. Therefore, the electrode having a high density can be easily wound up.

Next, the first mixture of the dried activated carbon and the conductive carbon powder is mixed with a binder having a composition as described above to form a second mixture, and then the second mixture is formed on a current collector made of a metal such as aluminum. The polarizing electrode of the electric double layer capacitor is manufactured by apply | coating and a pressing process, etc. Subsequently, the process of manufacturing an electric energy storage device such as an electric double layer capacitor using an electrode manufactured according to the present invention is similar to the process of manufacturing a conventional electric double charge capacitor.

In the present invention, since the viscosity of the second mixture in the form of slurry prepared by adding water and a binder to the first mixture can be variously adjusted according to the content of water and water-soluble chitosan, a thin thickness of about 0.005 mm on the current collector. Application of the active material becomes possible.

Table 2 measures the capacity and resistance of the electrical energy storage device including the electrode manufactured according to the present invention at a temperature of about 60 ℃.

         Classification ＼ Characteristics Initial capacity (F) Capacity after 1000 hours (F) Initial resistance (Ω㎝) Resistance after 1000 hours Measures 46.5 43.0 21.0 25.0

As shown in Table 2, when the initial capacity and the initial resistance of the electric energy storage device including the electrode manufactured according to the present invention are used after about 1,000 hours, the electricity after about 1,000 hours of use is compared. The capacity of the energy storage device is reduced by about 7.5% and the resistance is maintained by about 20%.

Therefore, the electrical energy storage device having the electrode according to the present invention exhibits a very small capacity reduction, while the internal binding force of the electrode is also greatly increased because the increase rate of the electrode resistance is relatively small.

The polarization electrode manufactured according to the above process has a high density of about 0.41 to 0.82 g / cc. In the case of conventional electric double layer capacitors, the electrode density is generally about 0.5 g / cc, but the electrode of the electric double layer capacitor according to the present invention has a high electrode density of up to about 0.82 g / cc and has a low resistance. The electrical energy storage device having such an electrode is suitable for electric and electronic devices such as an electric vehicle, an unmanned controlled airplane, an uninterruptible power supply, etc., which require such a large capacity.

Hereinafter, an electrical energy storage device and a method of manufacturing the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited to the following embodiments.

Example 1

Activated carbon and conductive carbon powder were first washed with a solvent containing acetone. As described above, it is possible to remove impurities such as carbon monoxide (CO) or carbon dioxide (CO ₂ ) from the activated carbon and the conductive carbon powder and increase the density of the electrode through the washing process.

Subsequently, after the first mixture of the washed activated carbon and the conductive carbon powder is introduced into the dryer, the activated carbon and the conductive carbon powder are dried for about 1 hour while maintaining the temperature in the dryer at about 170 ° C.

Subsequently, the powder was pulverized using the dried activated carbon and the conductive carbon powder, and then the pulverized activated carbon powder and the conductive carbon powder were mixed at a ratio of about 8: 2 to form a first mixture.

Next, a binder including about 5 to about 8 parts by weight of a water-soluble chitosan having a molecular weight of about 10,000 was prepared for the first mixture, and then a binder and water were added to the first mixture to form a second mixture in the form of a slurry. .

As described above, in the present embodiment, while mixing the first mixture and the binder, the water-soluble chitosan in the binder plays a very important role in forming the slurry into the slurry as it is dissolved in water and thus the ratio of activated carbon powder According to the surface area, the state of the slurry was adjusted by the addition amount of the water-soluble chitosan having an appropriate molecular weight.

Then, the second mixture was applied onto a current collector made of a metal such as aluminum, and a polarization electrode of the electrical energy storage device was manufactured by using a pressing process such as pressing.

Table 3 below is a measurement of the density of the electrode prepared according to this embodiment.

             Characteristics ＼ Electrode resistance Electrode Density Before Crimping (g / cc) Electrode Density After Crimping (g / cc) Water soluble chitosan content (parts by weight) 5 10 0.40 0.41 6 10 0.41 0.43 7 11 0.41 0.43 8 14 0.41 0.42

As shown in Table 3 above, when water-soluble chitosan was added to the binder according to the present embodiment, the electrode density was measured to slightly increase to about 2.4 to 7.5 after the electrode was pressed. In the present embodiment, since the viscosity of the second mixture in the form of slurry can be variously adjusted according to the content of water and water-soluble chitosan, the second mixture can be applied to the current collector with a thin thickness of about 0.005 mm. there was.

Example 2

In the present embodiment, except for the composition of the binder, the process of manufacturing the electrode of the electrical energy storage device is the same as in Example 1 described above, so a description thereof is omitted.

According to this embodiment, about 5 to 8 parts by weight of water-soluble chitosan and about 5 parts by weight of polyurethane as a thermosetting resin are added to the first mixture in which the activated carbon powder and the conductive carbon powder are mixed at a ratio of about 8: 2. The binder was prepared.

According to the present embodiment, since the binder is prepared by adding a thermosetting resin to the water-soluble chitosan, the binder increases the binding strength between the active materials constituting the electrode and also greatly increases the binding force between the active materials and the current collector. Large electrodes could be obtained.

The following Table 4 measures the resistance and density of the electrode prepared according to the present embodiment by dividing before and after the compression.

               Characteristics ＼ Electrode resistance Electrode Density Before Crimping (g / cc) Electrode Density after Crimping (g / cc) Water soluble chitosan content (parts by weight) Polyurethane content (parts by weight) 5 5 7 0.65 0.70 6 5 7 0.67 0.72 7 5 8 0.66 0.71 8 5 10 0.67 0.70

As shown in Table 4, when the electrode is prepared by adding a thermosetting resin containing a polyurethane resin in addition to the water-soluble chitosan to the binder, the density of the electrode subjected to the pressing process is at least about 0.7 g / cc or more It was measured to be a significant improvement over double layer capacitors.

On the other hand, the electrode of the electrical energy storage device manufactured according to this embodiment was measured to have a low resistance of about 7 ~ 10 Ωcm. In addition, the mechanical strength and the binding property of the electrode were also increased, while the ductility of the electrode was relatively decreased.

In this embodiment, although a polyurethane resin was used as the thermosetting resin, the same effect can be obtained when a binder is prepared by adding another thermosetting resin such as melamine resin, polyester resin or epoxy resin.

Example 3

Also in this embodiment, except for the composition of the binder, the process of manufacturing the electrode of the electrical energy storage device is the same as in Example 1 described above, and a description thereof is omitted.

According to the present embodiment, about 5 parts by weight of water-soluble chitosan and about 5 parts by weight of polyurethane, about 2 parts by weight of alcohol, and polyvinylidone-styrene are present in the first mixture of the activated carbon powder and the conductive carbon powder. A binder was prepared by adding about 2-4 parts by weight of copolymer and about 2-4 parts by weight of polytetrafluoroethylene.

In this embodiment, since the binder is prepared by adding alcohol, the polyvinylidone-styrene copolymer and the polytetrafluoroethylene can be smoothly dispersed in the binder, and the polyvinylidone-styrene copolymer and the poly in the binder The addition of tetrafluoroethylene allows the electrodes to have a high density.

In addition, since the electrode manufactured according to the present embodiment exhibits ductility, the ductility of the electrode is not lowered during manufacturing of the electrode by the pressing process at a temperature of about 100 ° C., thus easily winding the electrode having a high density together with the separator and the like. Could.

Table 5 measures the resistance of the electrode prepared according to the present embodiment and the density of the electrode before and after compression.

                                Characteristics ＼ Electrode resistance Electrode Density Before Crimping (g / cc) Electrode Density After Crimping (g / cc) Water soluble chitosan content (parts by weight) Polyurethane content (parts by weight) Alcohol (part by weight) Polyvinylidone-styrene copolymer content (part by weight) Polytetrafluoroethylene content (parts by weight) 5 5 2 2 3 8 0.70 0.79 5 5 2 3 2 8 0.72 0.82 5 5 2 4 2 9 0.71 0.80 5 5 2 2 4 9 0.72 0.80

As shown in Table 5, the electrode prepared according to the present embodiment was maximized at about 0.79-0.82 g / cc, and the electrode resistance was very low at about 8-9 ∼cm. In addition, binding between the active materials constituting the electrode and between the active material and the current collector is also maintained, while the ductility of the electrode is not reduced.

According to the present invention, a binder containing water-soluble chitosan, water-soluble chitosan and thermosetting resin, or water-soluble chitosan, thermosetting resin, alcohol, polyvinylidone-styrene copolymer, polytetrafluoroethylene, etc. may be used as a solvent containing acetone. Slurry having various viscosities can be prepared because it is mixed with the washed activated carbon and conductor carbon powder to form a mixture in the form of a slurry.

In addition, by using the binder having the above-described composition, the binding force between the active materials and the binding force between the active material and the current collector can be greatly improved to prepare an electrode having a high density of about 0.7 to 10 g / cc, and the electrochemical Phosphorus stability is also remarkably improved.

Furthermore, since the resistance of the electrode is much smaller than in the related art, it has a large capacitance and a long electrochemical stability from an electrode showing a high density and low resistance, and thus, an electric vehicle, an unmanned pilot plane, an uninterruptible power supply, or the like requiring a large capacity. Suitable electrical energy storage devices can be manufactured.

As described above, although described with reference to the preferred embodiments of the present invention, those skilled in the art various modifications of the present invention without departing from the spirit and scope of the present invention described in the claims below. And can be changed.

Claims (23)

delete delete delete delete delete delete delete delete delete delete In the electrical energy storage device, 3-10 parts by weight of water-soluble chitosan, 3-7 parts by weight of heat curable resin, polyvinylidone-styrene copolymer 1 to the mixture comprising activated carbon and conductive carbon, and the mixture to bind on the current collector An electrical energy storage device comprising an electrode having a binder comprising -5 parts by weight and 1-5 parts by weight of polytetrafluoroethylene. The method of claim 11, The binder further comprises 1-3 parts by weight of alcohol based on the mixture. The method of claim 12, The water-soluble chitosan has a molecular weight of 5,000 to 10,000, wherein the thermosetting resin is any one selected from the group consisting of polyurethane resin, melanin resin, polyester resin and epoxy resin. In the manufacturing method of the electrical energy storage device, Washing the activated carbon and the conductive carbon powder; Drying the washed powder; Mixing the dried powder to form a first mixture; Mixing a binder comprising water-soluble chitosan and water to the first mixture to form a second mixture; And Applying the second mixture onto a current collector to form an electrode. The method of claim 14, The activated carbon and conductive carbon powder is washed with a solvent containing acetone manufacturing method of an electrical energy storage device. The method of claim 14, The washed powder is dried for 0.5 to 1.5 hours at a temperature of 160 to 180 ℃ manufacturing method of an electrical energy storage device. The method of claim 14, The method of manufacturing an electrical energy storage device further comprises the step of pulverizing the dried powder. The method of claim 14, And the content of the conductive carbon relative to the activated carbon in the first mixture is 8: 2. The method of claim 14, The content of the water-soluble chitosan in the first mixture is 3 to 10 parts by weight based on the first mixture. The method of claim 19, The binder further comprises 3 to 7 parts by weight of the thermosetting resin with respect to the first mixture. The method of claim 20, The thermosetting resin is a method of manufacturing an electrical energy storage device, characterized in that any one selected from the group consisting of polyurethane resin, melamine resin, polyester resin and epoxy resin. The method of claim 20, The binder further comprises 1 to 5 parts by weight of polyvinylidene-styrene copolymer and 1 to 5 parts by weight of polytetrafluoroethylene with respect to the first mixture. The method of claim 22, The binder further comprises 1 to 3 parts by weight of alcohol based on the first mixture.