KR20200046546A - Manufacturing method of porous active carbon using lignocellulose biomass and manufacturing method of the supercapacitor usig the active carbon - Google Patents

Abstract

The present invention relates to a method for preparing partially crystalline activated carbon and a method for preparing a supercapacitor using the partially crystalline activated carbon. The method comprises steps of: preparing Lignocellulose biomass; immersing the Lignocellulose biomass into an alkaline solution containing at least one metal element selected from the group consisting of K, Na and Ca; covering an outlet of a reactor containing the Lignocellulose biomass and the alkaline solution, dropping inert gas into the reactor, and covering an inlet of the reactor; raising a temperature in the reactor up to 100-150°C and maintaining the temperature to structurally isolate the cellulose and lignin contained in the Lignocellulose biomass; and opening the outlet of the reactor and raising a temperature up to 600-950°C while injecting inert gas through the inlet of the reactor, and maintaining the temperature to activate the structurally isolated cellulose and lignin. According to the present invention, it is possible to prepare the partially crystalline activated carbon which represents a high specific surface area, excellent conductivity and high specific capacitance by using the Lignocellulose biomass, of which raw material is easily secured.

Description

Manufacturing method of partially crystalline activated carbon using lignocellulose biomass and manufacturing method of supercapacitor using the partially crystalline activated carbon {Manufacturing method of porous active carbon using lignocellulose biomass and manufacturing method of the supercapacitor usig the active carbon}

The present invention relates to a method for producing partially crystalline activated carbon and a method for manufacturing a supercapacitor using the partially crystalline activated carbon, and more specifically, it is manufactured using a lignocellulose biomass that is easy to secure raw materials. The present invention relates to a method of manufacturing partially crystalline activated carbon that exhibits high specific surface area, excellent conductivity, and high storage capacity, and a method of manufacturing a supercapacitor using the partially crystalline activated carbon.

Among the next-generation energy storage devices, supercapacitors are in the spotlight as next-generation energy storage devices due to their fast charging and discharging speed, high stability, and eco-friendly characteristics. A typical supercapacitor is composed of a porous electrode, a current collector, a separator, and an electrolyte.

The supercapacitor is also referred to as an electric double layer capacitor (EDLC) or an ultracapacitor (Ultra-capacitor), which is a pair of charge layers each having a different sign at the interface between an electrode and a conductor and an electrolyte impregnated therewith Electric double layer) is used, and it is a device that does not require maintenance because deterioration due to repetition of charge / discharge operation is very small. Accordingly, supercapacitors are mainly used in the form of backing up integrated circuits (ICs) of various electric and electronic devices, and recently, their use has been expanded to widely apply to toys, solar energy storage, and HEV (hybrid electric vehicle) power supplies. have.

Such a supercapacitor generally includes two electrodes of an anode and a cathode impregnated with an electrolyte, and a separator made of a porous material to prevent ions and short circuits by interposing between these two electrodes, and preventing electrolysis and short circuits. It has a unit cell composed of a gasket for preventing leakage and preventing insulation and short circuit, and a metal cap as a conductor for packaging them. Then, one or more unit cells configured as above (normally, 2 to 6 in the case of a coin type) are stacked in series and completed by combining two terminals of the positive electrode and the negative electrode.

The performance of the supercapacitor is determined by the electrode active material, electrolytic solution, etc., and in particular, the main performance such as the storage capacity is mostly determined by the electrode active material. Activated carbon is mainly used as the electrode active material, and the reserve capacity is known to be up to 19.3 F / cc based on the electrode of a commercial product. In general, activated carbon used as an electrode active material of a supercapacitor uses activated carbon having a high specific surface area of 1500 m 2 / g or more.

However, the porous activated carbon used as an existing electrode active material has a disadvantage of lower conductivity than materials such as carbon nanotubes or graphene.

Republic of Korea Patent Registration No. 10-1137719

The problem to be solved by the present invention can be produced using a lignocellulose biomass, which is easy to secure a raw material, and manufactures partially crystalline activated carbon exhibiting high specific surface area, excellent conductivity and high specific capacity. It is to provide a method and a method for manufacturing a supercapacitor using the partially crystalline activated carbon.

The present invention comprises the steps of preparing a lignocellulose biomass, and immersing the lignocellulose biomass in an alkaline solution comprising one or more metal elements selected from the group consisting of K, Na and Ca. , Shielding the outlet of the reactor containing the lignocellulosic biomass and alkali solution, flowing an inert gas into the reactor, and then shielding the inlet of the reactor, and heating and maintaining the inside of the reactor at 100 to 150 ° C. Structurally separating the cellulose and lignin contained in the lignocellulosic biomass, and opening the outlet of the reactor and injecting an inert gas through the inlet of the reactor while heating and maintaining at 600 to 950 ° C to structurally separate Including the steps to activate the cellulose and lignin Is provides a process for the preparation of partially crystalline active carbon.

The alkali solution may include one or more substances selected from the group consisting of KOH, NaOH, Ca (OH ₂ ) and NaHCO ₃ .

Alkyl ammonium fluoride may be mixed with the alkali solution to allow doping of heterogeneous elements.

The alkylammonium fluoride is selected from the group consisting of MgF ₂ , H ₂ SiF ₆ , NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , ALF ₃ and H ₂ TiF ₆ It may contain one or more substances.

The lignocellulosic biomass and the alkylammonium fluoride are preferably mixed in a weight ratio of 1: 0.05 to 1: 0.5.

After the activating step, cooling the reactor and removing the metallic gas remaining inside the reactor may be included.

The step of removing the metallic gas may include the step of removing the metallic gas by injecting anhydrous ethanol vapor into the reactor.

In the activating step, it is preferable to prevent the metallic gas from being released into the atmosphere by placing a discharge tank containing ethanol in the outlet of the reactor.

The partially crystalline activated carbon has a specific surface area higher than 2800 m 2 / g.

The partially crystalline activated carbon exhibits a conductivity higher than 15 S / m.

In addition, the present invention is a step of preparing a composition for a supercapacitor electrode by mixing a partially crystalline activated carbon, a conductive material, a binder, and a dispersion medium prepared by the above method, and compressing the composition for the supercapacitor electrode to form an electrode or , Forming the composition for the supercapacitor electrode on a metal foil to form an electrode, or pushing the composition for the supercapacitor electrode into a sheet to form a sheet by attaching it to a metal foil or a current collector, and forming the electrode in the form of an electrode. Forming a supercapacitor electrode by drying the resultant formed by using the supercapacitor electrode as an anode and a cathode, and disposing a separator to prevent short circuit between the anode and the cathode between the anode and the cathode, and The step of impregnating the positive electrode, the separator and the negative electrode with a non-aqueous electrolyte solution is included. The present invention provides a method for manufacturing a supercapacitor.

According to the present invention, it can be prepared using a lignocellulose biomass (Lignocellulose biomass), which is easy to secure the raw material, and can produce a partially crystalline activated carbon exhibiting high specific surface area, excellent conductivity and high specific capacity. .

By using the partially crystalline activated carbon as an electrode active material for the positive electrode and the negative electrode, a supercapacitor having high storage capacity and energy density can be manufactured.

1 is a view schematically showing a reactor.
2 is a cross-sectional view of a coin-type supercapacitor according to an example.
3 to 6 are views showing a wound type supercapacitor according to an example.
7 is a high resolution transmission electron microscope (HR-TEM) photograph of activated carbon prepared according to a comparative example.
8 is a high-resolution transmission electron microscope (HR-TEM) photograph of a partially crystalline activated carbon prepared according to Experimental Example 1.
9 is a view showing an X-ray diffraction (XRD) pattern of activated carbon prepared according to a comparative example.
10 is a view showing an X-ray diffraction (XRD) pattern of partially crystalline activated carbon prepared according to Experimental Example 1.
11 is a view showing a nitrogen adsorption and desorption curve of activated carbon prepared according to Comparative Example and partially crystalline activated carbon prepared according to Experimental Example 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those of ordinary skill in the art to fully understand the present invention and may be modified in various other forms, and the scope of the present invention is limited to the embodiments described below. It does not work.

In the description or claims of the present invention, when any one component "includes" another component, it is not limited to being interpreted as being composed only of the corresponding component unless specifically stated otherwise, and other components are further added. It should be understood that it can be included.

The method for preparing partially crystalline activated carbon according to a preferred embodiment of the present invention comprises preparing a lignocellulose biomass, and the lignocellulose biomass is selected from the group consisting of K, Na, and Ca. Immersing in an alkali solution containing the above metal elements, shielding the outlet of the reactor containing the lignocellulosic biomass and the alkali solution, flowing an inert gas into the reactor, and then shielding the inlet of the reactor; Heating and maintaining the inside of the reactor at 100 to 150 ° C. to structurally separate cellulose and lignin contained in the lignocellulosic biomass, and opening the outlet of the reactor and injecting an inert gas through the inlet of the reactor While raising and maintaining the temperature at 600-950 ℃ And a step of activating a ridoen cellulose and lignin.

The alkali solution may include one or more substances selected from the group consisting of KOH, NaOH, Ca (OH ₂ ) and NaHCO ₃ .

Alkyl ammonium fluoride may be mixed with the alkali solution to allow doping of heterogeneous elements.

The alkylammonium fluoride is selected from the group consisting of MgF ₂ , H ₂ SiF ₆ , NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , ALF ₃ and H ₂ TiF ₆ It may contain one or more substances.

The lignocellulosic biomass and the alkylammonium fluoride are preferably mixed in a weight ratio of 1: 0.05 to 1: 0.5.

After the activating step, cooling the reactor and removing the metallic gas remaining inside the reactor may be included.

The step of removing the metallic gas may include the step of removing the metallic gas by injecting anhydrous ethanol vapor into the reactor.

In the activating step, it is preferable to prevent the metallic gas from being released into the atmosphere by placing a balance tank containing ethanol at the outlet of the reactor.

The partially crystalline activated carbon has a specific surface area higher than 2800 m 2 / g.

The partially crystalline activated carbon exhibits a conductivity higher than 15 S / m.

A method of manufacturing a supercapacitor according to a preferred embodiment of the present invention comprises the steps of preparing a composition for a supercapacitor electrode by mixing partially crystalline activated carbon, a conductive material, a binder, and a dispersion medium prepared by the above method, and for the supercapacitor electrode The composition is compressed to form an electrode, or the supercapacitor electrode composition is coated on a metal foil to form an electrode, or the supercapacitor electrode composition is pushed with a roller to form a sheet and pasted onto a metal foil or current collector to form an electrode. Forming a form, drying the resultant formed in the form of an electrode to form a supercapacitor electrode, and using the supercapacitor electrode as an anode and a cathode, and short-circuiting the anode and the cathode between the anode and the cathode. A separator for prevention is disposed, and the anode, the separator and the And impregnating the cathode with a non-aqueous electrolyte.

Hereinafter, a method for producing partially crystalline activated carbon according to a preferred embodiment of the present invention will be described in more detail.

Prepare a lignocellulose biomass. Examples of the lignocellulose biomass include herbaceous biomass such as silver grass, wheat straw, corn stalk, rice straw, or wood biomass such as sawdust, twigs of waste wood, twigs, wood scraps, and peanut shells. For example. The lignocellulose biomass is a material that is commonly available in the surroundings, and has an advantage of easy to secure raw materials. The lignocellulose biomass may be pulverized and used. Lignocellulosic biomass, such as silver grass and corn stalk, is not properly utilized and discarded. In the present invention, economic and environmental benefits can be obtained by appropriately utilizing the biomass.

The lignocellulosic biomass is immersed in an alkali solution containing at least one metal element selected from the group consisting of K, Na and Ca. The alkali solution may be a solution containing one or more substances selected from the group consisting of KOH, NaOH, Ca (OH ₂ ) and NaHCO ₃ , and the alkali solution preferably has a concentration of 1M to 10M.

Generally, lignocellulose biomass is composed of hemicellulose, cellulose and lignin. Hemicellulose and cellulose are composed of carbohydrate polymers, and lignin is composed of aromatic polymers. Lignin, an aromatic polymer, is a component that can have crystallinity at high temperatures, and exhibits different properties from hemicellulose and cellulose, which are carbohydrate polymers. However, in the state where the main components coexist, it is difficult to exhibit the properties of the respective polymers, so that each component is structurally separated and subjected to an activation treatment, thereby inducing a porous structure in activated carbon and having partial crystallinity.

Alkyl ammonium fluoride may be mixed with the alkali solution to allow heterogeneous elements to be doped into partially crystalline activated carbon. The alkylammonium fluoride is selected from the group consisting of MgF ₂ , H ₂ SiF ₆ , NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , ALF ₃ and H ₂ TiF ₆ It may contain one or more substances. The lignocellulosic biomass and the alkylammonium fluoride are preferably mixed in a weight ratio of 1: 0.05 to 1: 0.5.

1 is a view schematically showing a reactor.

Referring to FIG. 1, the reactor 200 is provided with an inlet 210 through which an inert gas is introduced and an outlet 220 through which the inert gas is discharged. The opening and closing of the inlet 210 may use the first valve V1, and the opening and closing of the outlet 220 may use the second valve V2. The reactor 200 may be manufactured in a desired shape (for example, a cylinder, a square machine, etc.) by coating BN on a metal material plate to be an inner surface of the reactor.

The outlet 220 of the reactor containing the lignocellulose biomass and the alkali solution 240 is shielded, and an inert gas is flowed into the reactor 200, and then the inlet 210 of the reactor is shielded. The inert gas means nitrogen (N ₂ ), argon (Ar), helium (He), or a mixed gas thereof.

The inside of the reactor 200 is heated and maintained at 100 to 150 ° C (for example, for 10 minutes to 12 hours) to structurally separate cellulose and lignin contained in the lignocellulosic biomass. When the inside of the reactor 200 is heated to 100 to 150 ° C, the pressure inside the reactor 200 rises as the alkali solution changes to a vapor state. When the low-temperature heat treatment is performed while maintaining at 100 to 150 ° C in an inert gas atmosphere, the lignocellulosic biomass immersed in an alkali solution is structurally separated into solid cellulose, liquid hemicellulose, and lignin.

While opening the outlet 220 of the reactor and injecting an inert gas through the inlet 210 of the reactor, it is heated and maintained at 600 to 950 ° C to activate structurally separated cellulose and lignin. The activation is preferably performed in an inert atmosphere for 10 minutes to 12 hours at an activation temperature of 600 to 950 ° C, more preferably 650 to 900 ° C. It is preferable to increase the temperature up to the activation temperature at a heating rate of 0.1 to 50 ° C / min.

In the activating process, it is preferable to place the discharge tank 230 containing ethanol in the outlet 220 of the reactor to prevent metallic gas from being released into the atmosphere. The inert gas injected through the inlet 210 of the activation reactor is discharged through the outlet 220. At this time, it is preferable that the inert gas discharged through the outlet 220 is not directly discharged into the outside air. This is because it is dangerous because alkali components such as metallic gas may be discharged together with the inert gas discharged through the outlet 220. To this end, the outlet 220 is preferably connected to the discharge tank 230 containing liquid such as ethanol, and allows the inert gas to be discharged through the liquid contained in the discharge tank 230 to prevent the discharge to the outside air directly. Do.

The reactor 200 is cooled.

The metallic gas remaining inside the reactor 200 may be removed. To this end, anhydrous ethanol vapor may be injected into the reactor 200 to remove the metallic gas. It is preferable not to use methanol because it is toxic and may harm workers, and distilled water is not recommended because it may cause a fire or the like when mixed with metallic gas. In this way, by injecting anhydrous ethanol vapor, it is possible to effectively remove the alkali by-products deposited on the activated product. It is preferable that the anhydrous ethanol vapor is discharged through the outlet 220 to the discharge tank 230 containing the liquid.

In order to remove the alkali component buried in the partially crystalline activated carbon obtained after the activation, it may be washed with distilled water or the like and dried at a temperature of about 60 to 180 ° C. for 10 minutes to 24 hours.

The partially crystalline activated carbon thus prepared has a specific surface area higher than 2800 m 2 / g (eg, 2810 to 3300 m 2 / g). The partially crystalline activated carbon exhibits a conductivity higher than 15 S / m (eg, 15.1 to 18 S / m). In the case of partially crystalline activated carbon prepared by structurally separating cellulose and lignin through a low-temperature (100 to 150 ° C) heat treatment using an alkali solution, and activating at a high temperature (600 to 950 ° C) using an alkali solution. Since it has a specific surface area and some graffiti structure, when manufacturing an electrode using this, not only the capacity of the electrode but also the conductivity can be improved. In addition, since the decomposition and activation of the lignocellulosic biomass are performed in the same reactor, the chemicals used are simplified and the process is simplified and economical and environmental benefits are achieved. Disassembly and activation can be carried out at the same time, which simplifies the process and reduces the use of chemicals, making production more efficient.

The partially crystalline activated carbon thus prepared may be used as an electrode active material for manufacturing an electrode of a supercapacitor.

Hereinafter, a method of manufacturing a supercapacitor electrode and a supercapacitor using the partially crystalline activated carbon will be described.

A composition for a supercapacitor electrode is prepared by mixing the partially crystalline activated carbon, a conductive material, a binder, and a dispersion medium. The composition for the supercapacitor electrode is 2 to 20 parts by weight of the conductive material with respect to 100 parts by weight of the partially crystalline activated carbon and 100 parts by weight of the partially crystalline activated carbon, and 2 to 20 parts by weight of the binder with respect to 100 parts by weight of the partially crystalline activated carbon, and the part It may contain 200 to 300 parts by weight of the dispersion medium relative to 100 parts by weight of crystalline activated carbon. Since the composition for the supercapacitor electrode is in the form of a dough, uniform mixing (complete dispersion) may be difficult. For a predetermined time (for example, 10 minutes to 12 hours) using a mixer such as a planetary mixer. While stirring for a while, a composition for a supercapacitor electrode suitable for electrode production can be obtained. Mixers, such as planetary mixers, enable the preparation of compositions for uniformly mixed supercapacitor electrodes.

The binder is polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF; polyvinylidenefloride), carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB) ; poly vinyl butyral), polyvinylpyrrolidone (PVP), styrene butadiene rubber (SBR), polyamide-imide, polyimide, etc. One or two or more selected types can be used in combination.

The conductive material is not particularly limited as long as it is an electronically conductive material that does not cause chemical changes. Examples include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, super-P black, carbon fiber, copper, nickel , Metal powder such as aluminum, silver, or metal fiber.

The dispersion medium may be an organic solvent such as ethanol (EtOH), acetone, isopropyl alcohol, N-methylpyrrolidone (NMP), propylene glycol (PG) or water.

The composition for the supercapacitor electrode is compressed to form an electrode, or the composition for the supercapacitor electrode is coated on a metal foil to form an electrode, or the composition for the supercapacitor electrode is pushed with a roller to form a sheet and a metal foil or It is attached to the current collector to form an electrode.

If the example of forming the electrode is described in more detail, the composition for a supercapacitor electrode can be formed by compression using a roll press molding machine. The roll press forming machine aims to improve the electrode density and control the thickness of the electrode through rolling, a controller that can control the thickness and heating temperature of the upper and lower rolls and rolls, and a winding that can unwind and wind the electrodes. It consists of wealth. The rolling process proceeds as the rolled electrode passes through the roll press, and it is wound again into a rolled state to complete the electrode. At this time, the pressure of the press is preferably 5 to 20 ton / cm 2 and the roll temperature is 0 to 150 ° C. The composition for a supercapacitor electrode that has undergone the press compression process as described above undergoes a drying process. The drying process is performed at a temperature of 100 ° C to 350 ° C, preferably 150 ° C to 300 ° C. In this case, when the drying temperature is less than 100 ° C, evaporation of the dispersion medium is difficult, which is undesirable, and when drying at a high temperature exceeding 350 ° C, oxidation of the conductive material may occur, which is not preferable. Therefore, the drying temperature is preferably at least 100 ° C and does not exceed 350 ° C. In addition, the drying process is preferably performed at the above temperature for about 10 minutes to 6 hours. This drying process improves the strength of the supercapacitor electrode by drying the powdered composition for a supercapacitor electrode (evaporating the dispersion medium) and binding the powder particles.

In addition, looking at another example of forming an electrode, the supercapacitor electrode composition is coated on a metal foil, such as a titanium foil, an aluminum foil, or an aluminum etching foil. Alternatively, the electrode composition may be pressed into a roller to form a sheet (rubber type) and attached to a metal foil or metal current collector to produce an electrode. The aluminum etching foil means that the aluminum foil is etched in an uneven shape. A drying process is performed for the electrode shape that has undergone the above-described process. It is carried out at a temperature of 100 ℃ to 250 ℃, preferably 150 ℃ to 200 ℃.

The supercapacitor electrode is used as an anode and a cathode, the anode and the cathode are spaced apart, and a separator for preventing a short circuit between the anode and the cathode is disposed between the anode and the cathode, and the anode, the A supercapacitor may be manufactured by impregnating a separator and the cathode with a non-aqueous electrolyte.

As an example, the supercapacitor electrode manufactured as described above can be usefully applied to a small coin-type supercapacitor as a high capacity.

2 is a state diagram of the use of a supercapacitor according to the present invention, showing a cross-sectional view of a coin-type supercapacitor to which the supercapacitor electrode is applied. In FIG. 2, reference numeral 190 is a metal cap as a conductor, and reference numeral 160 is a separator made of a porous material for preventing insulation and short circuit between the anode 120 and the cathode 110, and reference numeral 192 is an electrolyte leakage. It is a gasket for preventing and preventing insulation and short circuit. At this time, the positive electrode 120 and the negative electrode 110 are firmly fixed by a metal cap 190 and an adhesive.

The coin-type supercapacitor is disposed between the positive electrode 120 made of the above-described supercapacitor electrode, the negative electrode 110 made of the above-described supercapacitor electrode, and the positive electrode 120 and the negative electrode 110, and the positive electrode 120. After separating the separator 160 to prevent a short circuit between the anode and the cathode 120 in the metal cap 190, and injecting an electrolyte in which electrolyte is dissolved between the anode 120 and the cathode 110, It can be manufactured by sealing with a gasket 192.

The separator may include a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, a polyester nonwoven fabric, a polyacrylonitrile porous separator, a poly (vinylidene fluoride) hexafluoropropane copolymer porous separator, a cellulose porous separator, a kraft paper or rayon fiber, and a battery and capacitor. If the separator is generally used in the field is not particularly limited.

On the other hand, the electrolyte is charged in the supercapacitor is propylene carbonate (PC; propylene carbonate), acetonitrile (AN; acetonitrile) and sulfolane (SL; sulfolane) selected from one or more solvents TEABF ₄ (tetraethylammonium tetrafluoborate) and TEMABF ₄ ( triethylmethylammonium tetrafluoborate) may be used. In addition, the electrolyte may include one or more ionic liquids selected from EMIBF ₄ (1-ethyl-3-methyl imidazolium tetrafluoborate) and EMITFSI (1-ethyl-3-methyl imidazolium bis (trifluoromethane sulfonyl) imide). .

3 to 6 are views showing a supercapacitor according to another example of the present invention, and a method for manufacturing a supercapacitor will be described in detail with reference to FIGS. 3 to 6.

The method for preparing a composition for a supercapacitor electrode by mixing the above-described partially crystalline activated carbon, a binder, a conductive material, and a dispersion medium is the same as the method described above.

The composition for the supercapacitor electrode is coated on a metal foil, such as aluminum foil or aluminum etching foil, or the composition for the supercapacitor electrode is pushed with a roller to a sheet state ( Rubber type) and attached to a metal foil or current collector to produce positive and negative electrodes.

The drying process is performed for the anode and cathode shapes that have undergone the above-described process. The drying process is performed at a temperature of 100 ° C to 350 ° C, preferably 150 ° C to 300 ° C. In this case, when the drying temperature is less than 100 ° C, evaporation of the dispersion medium is difficult, which is undesirable, and when drying at a high temperature exceeding 350 ° C, oxidation of the conductive material may occur, which is not preferable. Therefore, the drying temperature is preferably at least 100 ° C and does not exceed 350 ° C. In addition, the drying process is preferably performed at the above temperature for about 10 minutes to 6 hours. This drying process improves the strength of the supercapacitor electrode by drying the composition for the supercapacitor electrode (evaporating the dispersion medium) and binding the powder particles.

As shown in FIG. 3, the lead wires 130 and 140 are respectively applied to the positive electrode 120 and the negative electrode 110 prepared by coating the composition for a supercapacitor electrode on a metal foil or making a sheet to a metal foil or a current collector, respectively. Attach.

As shown in FIG. 4, the first separation membrane 150, the anode 120, the second separation membrane 160, and the cathode 110 are stacked and coiled to roll a winding device in the form of a roll ( 175), it is wound around the roll (roll) with an adhesive tape 170 or the like to maintain the roll shape.

The second separator 160 provided between the anode 120 and the cathode 110 serves to prevent a short circuit between the anode 120 and the cathode 110. The first and second separators 150 and 160 are polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyester nonwoven fabric, polyacrylonitrile porous separator, poly (vinylidene fluoride) hexafluoropropane copolymer porous separator, cellulose porous separator, kraft paper Or, if the separator is generally used in the field of batteries and capacitors, such as rayon fibers, is not particularly limited.

As shown in FIG. 5, a sealing rubber 180 is mounted on the result of a roll form, and is inserted into a metal cap (eg, an aluminum case) 190.

The roll-shaped winding element 175 (positive electrode 120 and negative electrode 110) is injected with an electrolyte to be impregnated and sealed. The electrolyte is a non-aqueous system, and one selected from tetraethylammonium tetrafluoborate (TEABF4) and TEMABF4 (triethylmethylammonium tetrafluoborate) in one or more solvents selected from propylene carbonate (PC), acetonitrile (AN) and sulfolane (SL). It is possible to use one in which more than one salt is dissolved. In addition, the electrolyte may be made of at least one ionic liquid selected from EMIBF4 (1-ethyl-3-methyl imidazolium tetrafluoborate) and EMITFSI (1-ethyl-3-methyl imidazolium bis (trifluoromethane sulfonyl) imide).

The supercapacitor thus manufactured is schematically illustrated in FIG. 6.

Hereinafter, experimental examples according to the present invention are specifically presented, and the present invention is not limited to the experimental examples presented below.

<Experimental Example 1>

High specific surface area partially crystalline activated carbon was prepared based on lignocellulose biomass.

Lignocellulose biomass was used by crushing the herbaceous giant silver grass.

50 ml of 6M potassium hydroxide aqueous solution and 10 g of crushed giant silver grass were mixed and maintained for 24 hours to sufficiently immerse the large silver grass in an aqueous potassium hydroxide solution, and then charged to the reactor 200 shown in FIG. 1. In order to shield the outlet 220 of the reactor and to create an inert atmosphere before decomposition and activation, argon (Ar) gas is flowed into the reactor at 300 cc / min through the inlet 210 for 1 hour to create an atmosphere. The inlet 210 was shielded. When all the openings and closings of the reactor are shielded, the pressure inside the reactor increases, and an environment in which the lignocellulosic biomass can be easily decomposed in an environment of high pressure and low temperature can be created.

The temperature of the reactor was raised to 100 ° C. and maintained for 1 hour to perform structural separation of lignocellulosic biomass into cellulose and lignin. At this time, the heating rate was set at 3 ° C / min.

After opening the outlet 220 of the reactor, argon (Ar) gas is injected at 300 cc / min through the inlet 210 and raised to 900 ° C. at a heating rate of 3 ° C./min and maintained at 900 ° C. for 1 hour. To activate the reaction. At this time, the discharge tank 230 containing ethanol was placed at the end of the discharge port 220 to prevent the metallic gas from being released into the atmosphere.

After activation is completed, the reactor is cooled, and anhydrous ethanol is injected through the inlet 210 for 15 minutes in a vapor state to remove potassium gas remaining inside the reactor, and then the sample is collected.

The collected sample was washed 5 times with 1 L of distilled water to approach pH 7, filtered using a vacuum filtration device, and dried in a convection dryer at 80 ° C. to obtain partially crystalline activated carbon.

<Comparative Example>

Activated carbon was prepared based on lignocellulose biomass.

Lignocellulose biomass was used by crushing the herbaceous giant silver grass.

50 ml of 6M potassium hydroxide aqueous solution and 10 g of crushed giant silver grass were mixed and maintained for 24 hours to sufficiently immerse the large silver grass in an aqueous potassium hydroxide solution, and then charged to the reactor 200 shown in FIG. 1.

After opening the outlet 220 of the reactor, argon (Ar) gas is injected at 300 cc / min through the inlet 210 and raised to 900 ° C. at a heating rate of 3 ° C./min and maintained at 900 ° C. for 1 hour. To activate the reaction. At this time, the discharge tank 230 containing ethanol was placed at the end of the discharge port 220 to prevent the metallic gas from being released into the atmosphere.

After activation is completed, the reactor is cooled, and anhydrous ethanol is injected through the inlet 210 for 15 minutes in a vapor state to remove potassium gas remaining inside the reactor, and then the sample is collected.

The collected sample was washed once with 1 liter of HCl aqueous solution and 5 times with 1 liter of distilled water to approach pH 7, filtered using a vacuum filtration device, and dried in a convection dryer at 80 ° C. to obtain activated carbon.

A gas analyzer (Belsorp-Mini II, BEL, Japan) was used to confirm the pore structure of activated carbon prepared according to Experimental Example 1 and Comparative Example, and BET (Brunauer-Emmett-Teller) was used from the nitrogen adsorption-desorption isotherm. Was used to obtain the specific surface area. High-resolution transmission electron microscope (HR-TEM) (JEOL, JEM-2000EX, Japan) and X-ray diffraction (XRD) (Rigaku D / Max) to confirm the crystalline structure 2500 / PC, Japan).

7 is a high resolution transmission electron microscope (HR-TEM) photograph of activated carbon prepared according to a comparative example, and FIG. 8 is a high resolution transmission electron microscope (HR-TEM) photograph of partially crystalline activated carbon prepared according to Experimental Example 1.

9 is a view showing an X-ray diffraction (XRD) pattern of activated carbon prepared according to a comparative example, and FIG. 10 is a view showing an X-ray diffraction (XRD) pattern of partially crystalline activated carbon prepared according to Experimental Example 1 to be.

Table 1 below shows surface resistance, specific resistance, and conductivity of activated carbon prepared according to Experimental Example 1 and Comparative Example.

sample surface
Resistance (Ω / sq) Resistance (Ω · cm) Specific resistance (Ω · m) Conductivity (S / cm) Conductivity (S / m) Experimental Example 1 287 6.03 0.06 0.17 16.59 Comparative example 597 7.03 0.07 0.14 14.22

Referring to FIGS. 7 to 10 and Table 1, a high resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD) analysis showed partial crystallinity, and the interlayer distance was in the range of 3.35 to 3.45 Å. The partially crystalline activated carbon prepared according to Experimental Example 1 exhibited a (002) peak closer to the graphite peak than the activated carbon prepared according to the comparative example. It was found that the conductivity of the partially crystalline activated carbon prepared according to Experimental Example 1 was higher than that of the activated carbon prepared according to the comparative example.

11 is a view showing a nitrogen adsorption and desorption curve of activated carbon prepared according to Comparative Example and partially crystalline activated carbon prepared according to Experimental Example 1.

Referring to FIG. 11, the partially crystalline activated carbon prepared according to Experimental Example 1 increased the amount of nitrogen adsorption and the amount of the intermediate pores, and as a result, the specific surface area of the partially crystalline activated carbon prepared according to Experimental Example 1 was 2885 m. ² / g, the specific surface area of the activated carbon prepared according to the comparative example was 2011 m ² / g.

<Experimental Example 2>

In order to analyze the electrochemical properties, the partially crystalline activated carbon prepared according to Experimental Example 1 and the activated carbon prepared according to the comparative example were used as electrode active materials, respectively, to prepare an electrode for a supercapacitor. At this time, in order to prepare a rubber-type electrode, 0.46 g of electrode active material based on 0.5 g, 0.025 g of Super-p as a carbon black type, and 0.015 g of polytetrafluoroethylene (PTFE) as a binder are added to ethanol as a dispersion medium, and After mixing for 3 minutes with a planetary mixer to form a slurry, the slurry was hand-kneaded and then rolled with a heating roll press. At this time, the pressurizing pressure of the press was 1 to 20 ton / cm 2, the temperature of the roll was 60 ° C., and the rotation speed was 300 rpm. The thickness after the rolling step was about 150 μm. The rolled product was placed in a vacuum drying bed at 150 ° C. and dried for 12 hours to form an electrode.

The electrode thus prepared was assembled into a cell of coin type 2032, and a full cell was assembled. At this time, the separator used was TF4035 from NKK. As the electrolyte, a solution in which 1 M TEABF ₄ salt was dissolved in acetonitrile (AcN) solution was used.

The cell thus manufactured is a constant current-constant voltage charging / discharging method (CC-CV galvanostatic charge / discharge method) for measuring capacitance change according to power storage capacity, current density, and voltage drop (IR-drop) during discharge. Was used. The equipment used for measuring the charge and discharge testing machine was used (BT48CH, Human technology, Korea) , 0.5, 1, 2, 5, 10, 20 mA / cm 2 Charging and discharging were performed at current density, and the results are shown in Table 2 below.

Current density (mA / cm ² ) 0.5 One 2 5 10 20 Reserve capacity (F / cc) Battery manufactured using activated carbon prepared according to Experimental Example 1 60.4 59.8 59.1 58.5 57.8 57.2 Battery produced using activated carbon prepared according to Comparative Example 36.84 36.72 36.6 36.2 35.64 34.8

Referring to Table 2, the discharge capacity of the battery prepared using the partially crystalline activated carbon prepared according to Experimental Example 1 is 0.5 mA / cm ² In the current density, 60.4 F / cc based on a half cell was satisfied. It also showed a 94.7% capacity retention rate at 20 mA / cm ² current density.

As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art.

110: cathode 120: anode
130: first lead wire 140: second lead wire
150: first separator 160: second separator
170: adhesive tape 175: winding element
180: sealing rubber 190: metal cap
192: gasket
200: reactor
210: inlet
220: outlet
230: discharge tank

Claims (11)

Preparing a lignocellulose biomass;
Immersing the lignocellulosic biomass in an alkali solution containing at least one metal element selected from the group consisting of K, Na and Ca;
Shielding the outlet of the reactor containing the lignocellulosic biomass and alkali solution, flowing an inert gas into the reactor, and then shielding the inlet of the reactor;
Heating and maintaining the inside of the reactor at 100 to 150 ° C. so that cellulose and lignin contained in the lignocellulosic biomass are structurally separated; And
The step of opening the outlet of the reactor and injecting an inert gas through the inlet of the reactor while heating and maintaining it at 600 to 950 ° C to activate structurally separated cellulose and lignin. Manufacturing method.
The method of claim 1, wherein the alkali solution comprises one or more substances selected from the group consisting of KOH, NaOH, Ca (OH ₂ ) and NaHCO ₃ .
The method according to claim 2, characterized in that a hetero element is doped by mixing an alkylammonium fluoride with the alkali solution.
The method of claim 3, wherein the alkylammonium fluoride is MgF ₂ , H ₂ SiF ₆ , NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , KF, KHF ₂ , ALF ₃ and H ₂ TiF. Method for producing a partially crystalline activated carbon comprising at least one material selected from the group consisting of ₆ .
The method of claim 2, wherein the lignocellulosic biomass and the alkylammonium fluoride are mixed in a weight ratio of 1: 0.05 to 1: 0.5.
According to claim 1, After the activating step,
Cooling the reactor; And
And removing the metallic gas remaining inside the reactor.
The method of claim 6, wherein the step of removing the metallic gas comprises the step of removing the metallic gas by injecting anhydrous ethanol vapor into the reactor.
According to claim 1, In the activating step,
Method for producing a partially crystalline activated carbon, characterized in that by placing a discharge tank containing ethanol in the outlet of the reactor to prevent the metallic gas is released into the atmosphere.
The method of claim 1, wherein the partially crystalline activated carbon has a specific surface area higher than 2800 m 2 / g.
The method of claim 1, wherein the partially crystalline activated carbon has a conductivity higher than 15 S / m.
A method for preparing a composition for a supercapacitor electrode by mixing a partially crystalline activated carbon, a conductive material, a binder, and a dispersion medium prepared by any one of claims 1 to 9;
The composition for the supercapacitor electrode is compressed to form an electrode, or the composition for the supercapacitor electrode is coated on a metal foil to form an electrode, or the composition for the supercapacitor electrode is pushed with a roller to form a sheet and a metal foil or Attaching to the current collector to form an electrode;
Drying the resultant formed in the form of an electrode to form a supercapacitor electrode; And
The supercapacitor electrode is used as an anode and a cathode, and a separator for preventing a short circuit between the anode and the cathode is disposed between the anode and the cathode, and the anode, the separator and the cathode are impregnated with a non-aqueous electrolyte. Method of manufacturing a supercapacitor comprising a step.

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