KR20060053484A - Method for manufacturing of active carbon electrode using super-capacitor and pellet type active carbon electrode manufactured thereof - Google Patents

Abstract

The present invention relates to a method of manufacturing an electrode for an ultracapacitor and a pellet-type electrode manufactured accordingly. The present invention comprises the steps of obtaining a mixture of activated carbon powder, a mixture of activated carbon powder, a binder, a conductive agent and a dispersion medium to obtain a mixture of activated carbon in a dough formed by further adding molasses to improve adhesion between the activated carbon powder particles; Filling the activated carbon mixture into a mold according to the shape of an electrode, and then pressing the molded article with a press; Sintering the compacted molded product at 150 ° C. to 400 ° C .; to provide a method of manufacturing an activated carbon electrode for an ultracapacitor, and a pellet-type activated carbon electrode prepared by the same method as described above. do. According to the present invention, the electrode density is dramatically increased by the addition of molasses and the pressing process, which has a high capacity per unit volume, and there is no electrode loss, thereby greatly reducing yield and cost.

Ultracapacitors, Electrodes, Activated Carbon, Pellets, Electrode Density, Capacitance

Description

METHODS FOR MANUFACTURING OF ACTIVE CARBON ELECTRODE USING SUPER-CAPACITOR AND PELLET TYPE ACTIVE CARBON ELECTRODE MANUFACTURED THEREOF}             

1 is a process chart for explaining a method for manufacturing an electrode according to the prior art.

2 is a process chart for explaining a method for manufacturing an electrode according to the present invention.

3 is a cross-sectional view of a coin type capacitor as a state diagram of an electrode according to the present invention.

Explanation of symbols on the main parts of the drawings

10 electrode 20 metal cap

30: separator 40: gasket

120: mold 125: mold

140: Press

The present invention relates to a method of manufacturing an electrode for an ultracapacitor and a pellet-type electrode manufactured accordingly. More specifically, by adding molasses to improve the adhesion between the activated carbon particles to prepare a mixture of activated carbon on the dough, and filling the activated carbon mixture into a mold according to the shape of the electrode, then pressed and sintered to produce a pellet form to achieve high density Therefore, the present invention relates to a method of manufacturing an activated carbon electrode for an ultracapacitor having a high capacity per volume and an electrode loss, which is advantageous in yield and manufacturing cost, and a pellet-type activated carbon electrode prepared according to the present invention.

Supercapacitors are also commonly referred to as Electric Double Layer Capacitors (EDLCs), Super-capacitors or Ultra-capacitors, which are made up of electrodes and conductors and the electrolyte solution impregnated thereon. By using a pair of charge layers (electric double layers) each having a different sign at the interface, deterioration due to repetition of the charge / discharge operation is very small and requires no maintenance. As a result, ultracapacitors are mainly used in the form of IC backup of various electric and electronic devices. Recently, their applications have been widely applied to toys, solar energy storage, HEV power supplies, and the like.

The supercapacitor as described above generally includes two electrodes of an anode and a cathode impregnated with an electrolyte, and a separator made of a porous material for allowing only ion conduction and preventing insulation and short circuit between the two electrodes. It has a unit cell composed of a gasket for preventing leakage of an electrolyte solution and for preventing insulation and short circuit, and a metal cap as a conductor for packaging them. One or more unit cells (usually, 2 to 6 in the case of a coin type) configured as described above are stacked in series and completed by combining two terminals of a positive electrode and a negative electrode.

The electrode constituting the ultra-capacitive capacitor mainly uses activated carbon as an electrode active material. The capacitance of the ultracapacitor is determined by the amount of charge accumulated in the electric double layer, and the amount of charge becomes larger as the surface area of the electrode is larger. Therefore, activated carbon has a high specific surface area of 300 m 2 / g or more, and thus is suitable as an electrode material for an ultra high capacity capacitor that requires a large surface area.

An ultracapacitor using activated carbon powder as an electrode is disclosed in Japanese Patent Laid-Open No. 4-44407. The electrode proposed in this publication is a solid activated carbon electrode obtained by solidifying a mixture of activated carbon powder with a thermosetting resin such as a phenol resin.

In general, activated carbon for electrode production of ultracapacitors has a specific surface area of 1500 m 2 / g or more. Recently, however, the most difficult thing in manufacturing electrodes for ultracapacitors has been newly faced with the problem that it is difficult to increase the capacity per volume due to the electrode active material having a high specific surface area. In other words, when activated carbon having a high specific surface area is used, the capacity per unit mass is increased, but the electrode density is decreased due to the high specific surface area, and thus the capacity of the activated carbon is lowered compared to the unit volume. Accordingly, Japan Electronics (JEOL), Okamura Research Institute, etc. continue to show the results of expressing a high capacity using a low specific surface area activated carbon powder of less than 1000 m2 / g.

Conventionally, two methods are mainly used to manufacture an activated carbon electrode for an ultracapacitor.

The first method is to prepare an electrode by coating an activated carbon mixture in the form of a slurry of activated carbon, a binder, a conductive agent, and a dispersion medium on an aluminum foil, and then cutting or punching to a predetermined size after drying. Way)

In the second method, the activated carbon mixture in the form of a paste mixed with activated carbon, a binder, a conductive agent, and a dispersion medium is stretched and rolled into two rolls and processed into a sheet, and the sheet is cut or punched to form an electrode. It is a method of manufacturing. (Rolling method)

1 is a process chart for explaining an electrode manufacturing method (rolling method) according to the prior art, which is prepared by stretching the rolled activated carbon mixture into a sheet 1, and then punching the sheet (1) The electrode 2 is shown.

However, the conventional activated carbon electrode 2 manufactured as described above has an electrode density of about 0.5 to 0.6 g / cm 3, which acts as a large factor in limiting capacity expression per volume. In addition, since only a portion of the electrode is used by cutting and punching, there is a problem in that a loss rate of the electrode is also higher than 10%. In other words, the electrode density is small, so that the high capacity per volume is not exerted, and as shown in FIG. 1, the excess sheet 1 is discarded after being cut or punched, resulting in a large amount of electrode loss, which leads to a decrease in yield and an increase in manufacturing cost. There is a problem.

The present invention has been invented to solve the above-described problems, and the method of manufacturing an activated carbon electrode for an ultra-capacitor capacitor, which has high capacity per volume and is capable of implementing high density, has no electrode loss, and is advantageous in yield and manufacturing cost, and It is an object to provide an activated carbon electrode in the form of pellets prepared accordingly.

In order to achieve the above object, the present invention provides a method of manufacturing an activated carbon electrode for an ultracapacitor,

Obtaining an activated carbon mixture in a dough formed by further adding molasses to improve adhesion between the activated carbon powder particles to a mixture of activated carbon powder, a binder, a conductive agent and a dispersion medium;

Filling the activated carbon mixture into a mold according to the shape of an electrode, and then pressing the molded article with a press;

It provides a method for producing an activated carbon electrode for a high capacity capacitor comprising a; sintering the compacted molding at 150 ℃ ~ 400 ℃.

In addition, the present invention provides a new form of activated carbon electrode, that is, a pellet (Active carbon) electrode produced by the manufacturing method as described above. And the electrode according to the present invention has the same shape as the shape of the mold.

According to the present invention, the electrode density is increased by the addition of molasses and the pressing process by pressing, thereby having a high capacity per unit volume. In addition, since there is no conventional cutting or punching process, there is no electrode loss, and an electrode having a desired shape can be obtained according to the shape of the mold, so that the production is simple, and the strength of the electrode is improved by sintering.

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

2 is a process chart for explaining a method of manufacturing an electrode according to the present invention, Figure 3 is a state diagram of the use of the electrode according to the present invention, a cross-sectional view showing the electrode applied to the coin-type capacitor according to the present invention.

The activated carbon mixture 10 'used in the production of the electrode of the present invention is composed of activated carbon powder, a binder, a conductive agent and a dispersion medium as essential components as usual. At this time, the activated carbon mixture 10 'is a dough phase in which a small amount of dispersion medium is used according to the present invention. In addition, according to the present invention, molasses for improving adhesion between the activated carbon powder particles is further added to the activated carbon mixture 10 '. That is, the activated carbon mixture 10 'used in the preparation of the electrode of the present invention is a dough phase in which a small amount of a dispersion medium is used, and the activated carbon powder, the binder, the conductive agent, the dispersion medium, and the molasses are mixed.

According to the present invention, the activated carbon powder particles (especially in the form of tubes) have elasticity due to the spaces between the pores and the particles formed thereon, so that the activated carbon powder particles cannot be solidified into a tight structure even though they are compressed and do not have any binders. It was found that the separation was caused to reduce the electrode density. To this end, in the present invention, molasses is added as a functional additive (binder), and the pressing process by the press 140 (see FIG. 2) is performed. That is, molasses increases the packing density by improving the adhesion between the activated carbon particles, the pressing process by the press 140 further improves the density. This in turn improves the electrode density resulting in a high capacity per unit volume.

A method of obtaining the activated carbon mixture 10 'is described in detail.

First, a powder mixture in which powdered conductive agents are mixed with activated carbon powder is obtained by dry mixing. Separately from this, a binder and molasses are added to a small amount of the dispersion medium and sufficiently dispersed by wet mixing to obtain a binder solution. The powder mixture and binder solution are then mixed to obtain a mixture of activated carbon 10 'on the dough. At this time, since the activated carbon mixture 10 'is a dough phase, it may be difficult to uniformly mix (completely disperse), and if the mixture is stirred for a predetermined time using a planetary mixer, a mixture suitable for preparing an electrode of the present invention may be obtained. have. In other words, a planetary mixer enables the production of a dough-like activated carbon mixture 10 'of uniform mixing.

As the activated carbon powder, any activated carbon used in the preparation of the electrode according to the present invention may be used. For example, coconut shell-based activated carbon, phenol resin-based activated carbon, and the like may be used, which includes a nanotube form. In addition, carbon black may be usefully used as the conductive agent, and the binder may be polytetrafluoroethylene (PTFE; poly-tetrafluoroethylene), polyvinylidene fluoride (PVdF; polyvinylidenefloride), carboxymethylcellulose (CMC) or carboxymethylcellulose (poly). Selected from vinyl alcohol (PVA; poly vinyl alcohol), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP; poly-N-vinylpyrrolidone), styrene butadiene rubber (SBR) It can be used 1 type or in mixture of 2 or more types. The dispersion medium may be an organic solvent such as ethanol (EtOH), methyl pyrrolidone (NMP), or water.

In addition, in the blending amount of the activated carbon mixture 10 ', the conductive agent is preferably 5-30 parts by weight, 5-10 parts by weight of the binder, and 0.1-8 parts by weight of molasses, based on 100 parts by weight of the activated carbon powder. . The dispersion medium is not particularly limited but may be added in a small amount up to 35 parts by weight to form a dough. Preferably, the dispersion medium is composed of 8 to 30 parts by weight based on 100 parts by weight of the activated carbon powder.

The activated carbon mixture 10 'as described above is press-molded by the press 140 according to the present invention. 2 is a process diagram for explaining a method for manufacturing an electrode according to the present invention, which is a schematic configuration of a press molding machine 100 used in manufacturing the electrode of the present invention is illustrated. As shown in FIG. 2, the press molding machine 100 includes a molding die 120 in which the mold 125 is formed, and a press 140 installed on the upper end of the molding die 120 to move up and down. The activated carbon mixture 10 ′ is charged and filled into the mold 125 of the mold 120 and then press-molded by pressing the press 140. At this time, the shape of the mold 125 is the same as the shape of the electrode 10 to be targeted. In addition, although FIG. 2 illustrates a state in which one mold 125 is formed in the mold 120, a plurality of molds 125 are formed in the mold 120. Of course, when a plurality of molds 125 are formed, a plurality of presses 140 are installed in the same number. And the vertical movement of the press 140 may be used, such as hydraulic, pneumatic or electric press (cam method). At this time, the pressurized pressure of the press 140 may be 5 to 20 ton / cm 2.

The electrode 10 which has been subjected to the press crimping process as described above is subjected to the sintering process according to the present invention. Sintering process is carried out at 150 ℃ ~ 400 ℃. Preferably it is carried out at a temperature of 150 ℃ to 300 ℃. At this time, when the sintering temperature is less than 150 ℃ difficult evaporation of the dispersion medium is not preferable, and during the high temperature sintering exceeding 400 ℃ is not preferable because oxidation of the conductive agent (carbon black) and deformation of the binder occurs. The sintering temperature must therefore be at least 150 ° C. and not exceed 400 ° C. And the sintering process is recommended to proceed for about 2 to 6 hours at the above temperature. This sintering process dries the electrode 10 (evaporates the dispersion medium) and simultaneously binds the powder particles to improve the strength of the electrode 10.

The electrode 10 according to the present invention manufactured as described above can be applied directly to the capacitor (product) without a separate finishing process (cutting, punching, etc.), which is the same shape as the shape of the mold 125 as a pellet (pellet) Has And the electrode 10 of the present invention manufactured as described above has an electrode density of 0.5 ~ 2g / ㎠, it is possible to implement a capacity of 30F / cc or more.

The electrode 10 according to the present invention can be usefully applied to a small coin-type capacitor as an ultra high capacity. 3 is a state diagram of the use of the electrode 10 according to the present invention, showing a cross-sectional view of a coin-type capacitor to which the electrode 10 is applied. In FIG. 3, reference numeral 20 denotes a metal cap as a conductor, reference numeral 30 denotes a separator made of a porous material for preventing insulation and short circuit between the upper and lower electrodes 10, and reference numeral 40 denotes an electrolyte solution to prevent leakage and insulation. And gaskets for short circuit protection. At this time, the electrode 10 is firmly fixed by the metal cap 20 and the adhesive.

Hereinafter, specific test examples and comparative examples of the present invention will be described. However, the following examples are merely provided to explain the present invention in more detail, and do not limit the technical scope of the present invention.

EXAMPLE

100 parts by weight of YP17 activated carbon (manufactured by Kuraray Chemical, Japan) and 10 parts by weight of Super-p black (manufactured by Kuraray Chemical, Japan) as a conductive agent were dry mixed. Separately, 10 parts by weight of PVA and 5 parts by weight of molasses (domestic molasses) were mixed with 35 parts by weight of water. The two mixtures were added to a Planetary mixer (manufacturer: T.K, model name: Hivis disper), mixed and stirred for 40 minutes to completely disperse to obtain a mixture of activated carbon on a dough.

Next, the activated carbon mixture was filled in the mold 125 of the press molding machine 100 as shown in FIG. 2, and then pressed at a pressure of 12 ton / cm 2 for 2 seconds. The pressed molding was put into an electric oven (manufactured by International Engineering Co., Ltd.) maintained at 250 ° C., dried for 3 hours, and sintered to prepare an electrode specimen having a diameter of 12 mm and a height of 700 μm.

Applying the prepared electrode specimens to a coin cell of diameter 18.5mm, height 2mm to measure the electrode density, capacity, equivalent series resistance (ESR), leakage current is shown in Table 1 below. In this case, in preparing a coin cell, the electrolyte solution used was PC / TEABF4 1M. The charge was performed for 30 minutes to 2.5V at 100mA, and the discharge was performed at 2.5mA to 1V at 1mA. Equivalent series resistance (ESR) was performed at 1 KHz, and leakage current was set to a value charged for 30 minutes at 2.5V.

[Comparative Example]

The electrode manufactured by the conventional extending | stretching method was made into this comparative example. That is, molasses-free activated carbon mixture (YP17 activated carbon: Super-p black: PTFE: ethanol mixed at a weight ratio of 100: 8: 15: 80) in the form of no molasses was rolled and stretched, followed by punching. The prepared electrode specimens were applied to a coin cell. And the electrode density, capacity, equivalent series resistance (ESR), leakage current was measured in the same manner as in the above embodiment, the results are shown in Table 1 below.

            <Comparison of electrode characteristics according to manufacturing method> division                                              Comparative example Example Electrode density                                              0.61 g / cm 3 0.84 g / cm 3 Volume                                              2.35F / cc 2.74F / cc ESR                                              2.8Ω 2.4 Ω Leakage current                                              160㎂ 160㎂

As shown in Table 1, the pellet electrode (Example) according to the present invention can be seen that the electrode density is improved by more than 30% even when using the same activated carbon as compared to the comparative example according to the prior art, It can be seen that the capacity per unit volume was also improved by more than 16%.

In addition, the ESR also shows an improved value due to the improved electrode density, and it can be seen that the present invention implements the overall characteristic improvement of the ultracapacitor.

As described above, the present invention has the effect of having a high capacity per unit volume by dramatically increasing the electrode density in the pressing process by the addition of molasses and pressing.

In addition, it is possible to obtain the electrode of the desired shape according to the shape of the mold without cutting or punching process, the production is simple, and there is no electrode loss amount above all, it has a great effect on yield and cost reduction.

Claims (4)

In the manufacturing method of the activated carbon electrode for the ultracapacitor, Obtaining an activated carbon mixture in a dough formed by further adding molasses to improve adhesion between the activated carbon powder particles to a mixture of activated carbon powder, a binder, a conductive agent and a dispersion medium; Filling the activated carbon mixture into a mold according to the shape of an electrode, and then pressing the molded article with a press; Sintering the compacted molded product at 150 ℃ ~ 400 ℃; method for producing an activated carbon electrode for a high capacity capacitor, characterized in that it comprises a. The method of claim 1, wherein the press has a pressure of 5 to 20 ton / cm 2. In an activated carbon electrode for an ultracapacitor, The activated carbon electrode for ultracapacitors, which is manufactured by the method of claim 1 or 2, and has a pellet form. The activated carbon electrode of claim 3, wherein the electrode has an electrode density of 0.5 to 2 g / cm 3.

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