Carbon material for supercapacitor electrode and method for producing same

Abstract

An embodiment of the present invention provides: a carbon material for a supercapacitor electrode, the carbon material having a plurality of pores, wherein the pore volume of pores having a pore diameter of at most 17 Å among the plurality of pores is at most 30% of the total pore volume; a supercapacitor electrode including same; and a supercapacitor.

Description

Carbon material for electrode of supercapacitor and method for manufacturing same

[0001] The present disclosure relates to a carbon material for an electrode of a supercapacitor, a method for manufacturing the same, an electrode of a supercapacitor including the same, and a supercapacitor, and more specifically, to a carbon material for an electrode of a supercapacitor including the same, a carbon material for an electrode of a supercapacitor, and a supercapacitor having a high electrode density, a high energy density, and a low direct current resistance (ESR). DC ) and a carbon material for electrodes of a supercapacitor for providing a supercapacitor having the characteristics of high power density, a method for manufacturing the same, an electrode of a supercapacitor including the same, and a supercapacitor.

[0002]

[0003] Recently, electric double layer capacitors (EDLCs), also known as super capacitors, are being considered for application to various systems for efficient energy management, such as electric vehicles (EVs), energy storage systems (ESSs), and renewable energy.

[0004] In particular, supercapacitors can supplement batteries used as the main power source for electric vehicle operation by providing high-power energy required for rapid acceleration of electric vehicles and recovering energy generated instantaneously, thereby enabling commercial operation of electric vehicles.

[0005] Supercapacitors must store enough energy to provide the energy required for driving, and to effectively manage the cost, volume, and weight associated with this, supercapacitors must have very high power density per volume and weight, long life, and low cost.

[0006] Compared with conventional electrolytic capacitors, polymer capacitors, tantalum capacitors, etc., a supercapacitor (or electric double layer capacitor (EDLC)) uses a porous activated carbon series electrode to form a large effective surface area and stores energy in the electric double layer formed at the interface between the electrolyte and the electrode, thereby providing a high volumetric capacitance density (about 10 to 100 times that of a conventional capacitor).

[0007] However, there are also technical challenges associated with current supercapacitors.

[0008] Typically, experimentally measured capacitances in supercapacitors based on activated carbon electrodes are much smaller than the theoretical capacitances calculated from the analyzed specific surface area and width of the dipole layer.

[0009] In activated carbons with very high surface areas, the measured capacities are less than about 20% of the theoretical capacities, and this result is related to the presence of micropores (on the order of less than 2 nm), which have wetting deficiencies that prevent the electrolyte from accessing some of the pores, and in which the charged surfaces are separated by about 1 nm to 2 nm (10 Å to 20 Å), an electric double layer cannot be successfully formed.

[0010] Additionally, depending on the carbon source and heat treatment temperature in activated carbon, a large portion of the surface takes the form of micropores that are inaccessible to the liquid electrolyte.

[0011] Therefore, despite having high theoretical capacities at the electrode level, activated carbon electrodes do not provide energy storage devices with huge capacities at the supercapacitor cell or pack level.

[0012] Accordingly, new electrode materials are required that have high mass loading (areal density), high apparent density (high tap density), thick electrode thickness without significantly reducing electron and ion transport rates, high capacitance, high energy density and high power density.

[0013] [Prior Art Literature]

[0014] [Patent Document]

[0015] (Patent Document 1) Republic of Korea Patent Publication No. 10-2021-0149993 (December 10, 2021)

[0016] The present invention aims to provide a carbon material for a supercapacitor that includes pores with a high pore volume and an optimal diameter range through which solvent molecules of an electrolyte can sufficiently penetrate, has low DC resistance characteristics, high power density, and excellent capacitance retention.

[0017]

[0018] The present invention, as one embodiment, provides a carbon material for an electrode of a supercapacitor having a plurality of pores, wherein the pore volume of pores having a pore diameter of 17 Å or less among the plurality of pores is 30% or less of the total pore volume, an electrode of a supercapacitor including the same, and a supercapacitor.

[0019]

[0020] A carbon material according to one aspect of the present invention has an optimal pore diameter range, and by using it as a material for an electrode of a supercapacitor, a supercapacitor having low DC resistance characteristics, high power density, and excellent capacitance retention can be provided.

[0021]

[0022] Figure 1 shows a carbon material according to one embodiment of the present invention.

[0023] Figure 2 shows the BET analysis results of a carbon material manufactured according to a manufacturing example of the present invention.

[0024] Figure 3 shows the BET analysis results of commercial activated carbon (YP-50).

[0025] Figure 4 shows a Raman spectrum of a carbon material manufactured according to a manufacturing example of the present invention.

[0026] Figure 5 shows the Raman spectrum of commercial graphene.

[0027] Figure 6 shows the results of measuring the electrical conductivity of a carbon material manufactured according to a manufacturing example of the present invention.

[0028] Figure 7 shows the results of electrical conductivity measurement of commercial activated carbon (YP-50).

[0029] Figures 8 to 11 show the TEM analysis results of carbon materials manufactured according to the manufacturing examples of the present invention.

[0030]

[0031] The present invention will now be described in detail with reference to the attached drawings. However, it should be noted that the present invention is not limited to the contents described herein or the attached drawings. Those skilled in the art will be able to implement the present invention in various forms, based on the contents described herein and the attached drawings, without departing from the technical spirit of the present invention. It should be understood that such modifications also fall within the scope of the present invention.

[0032] Conventional supercapacitor polarizable electrodes are electrochemically inactive and have a large surface area (1,000 m 2 / g to 3,500m 2 / g) Activated carbon materials are commonly used. However, when manufacturing an electrode using activated carbon with a large specific surface area, the electrostatic capacity per mass of the activated carbon in the electrode increases, but there is a problem in that the void portion of the activated carbon increases, reducing the electrode density and the electrostatic capacity per volume of the activated carbon in the electrode decreases.

[0033] In addition, the pores of activated carbon particles for electrodes of supercapacitors require suitable conditions for the electrolyte to approach, and accordingly, it is possible to consider manufacturing a supercapacitor with high electrostatic capacity using a carbon electrode material with an optimal pore diameter by considering the sizes of the cations and anions to be adsorbed.

[0034] In particular, in supercapacitors using organic electrolytes, which have larger solvent molecules than those using aqueous electrolytes, anions and cations must move through the organic solvent molecules or be adsorbed on the activated carbon. Therefore, it is necessary for organic solvent molecules to sufficiently penetrate into the pores of the activated carbon, and for cation or anion molecules to move through the organic solvent molecules and be adsorbed on the surface of the activated carbon to form an electric double layer. Therefore, organic electrolytes require a pore distribution of activated carbon that is different from that of aqueous electrolytes.

[0035] Typically, when calculated from the geometric structure of cyclic carbonate solvent molecules, the distance between the hydrogen of the methyl group of propylene carbonate and the oxygen of the carbonyl group is approximately 8.6 Å, and for butylene carbonate, it is approximately 10 Å, and for chain-like solvent molecules, the distance between molecular segments is expected to increase relatively.

[0036] Therefore, in order for such large solvent molecules to smoothly penetrate into the pores of activated carbon, activated carbon having a large number of pores with a radius sufficiently larger than the solvent molecules is required.

[0037] Meanwhile, there are cases where graphene monolayer sheets are used to construct electrode bodies for supercapacitors by taking advantage of their high electrical conductivity and large surface area characteristics. However, in this case, there is a multilayer structure behavior between the graphene monolayer sheets, the binding between the fine monolayer structures by the binder is not smooth, and it is difficult to form the electrode body in a thick shape, which limits its formation in the form of a thin film. Furthermore, the high manufacturing cost of graphene makes it economically uncompetitive, and actual commercialization is not easy.

[0038]

[0039] Accordingly, in the present invention, in a supercapacitor, particularly a supercapacitor using an organic electrolyte, the relationship between the size of the electrolyte molecule, the pore distribution of the electrode material, and the electrostatic capacity was studied through BET (Brunauer, Emmett, and Teller) measurement, and as a result, a carbon material having a plurality of pores and a pore distribution in which the volume of pores having a pore diameter of 17 Å or less among the plurality of pores is 30% or less of the total pore volume was used as an electrode material of the supercapacitor.

[0040] In this specification, the crystal structure of carbon materials is similar to graphite crystals in that the planes are parallel and equally spaced, but it is composed of an imperfect amorphous structure in which the layers are irregularly stacked. This crystal structure forms countless nanometer-sized spaces, and in this specification, these spaces are called pores. The pores are classified into three levels: macropores, mesopores, and micropores, depending on their size, and pores of all sizes exist.

[0041] In this specification, “pore volume” means the total volume of all pores.

[0042] In addition, a carbon material having a large number of relatively large pores having a pore diameter exceeding 17 Å, preferably 17 Å to 500 Å, suitable for the penetration of organic electrolyte molecules and the adsorption of ionic molecules was manufactured, and this was used as an electrode material for a supercapacitor using an organic electrolyte. Accordingly, it was confirmed that organic electrolyte molecules can smoothly penetrate into the pores, and ionic molecules can be adsorbed on the surface of the carbon material to efficiently form an electric double layer.

[0043] In addition, the present invention provides a method for manufacturing a carbon material having a multilayer structure with a large number of relatively large pores having a pore diameter of 17 Å to 500 Å as well as a single-layer or multi-layer structure as can be seen through Raman analysis, and a carbon material manufactured thereby, which has the characteristic that the specific surface area does not decrease even when re-laminated, has a low manufacturing cost, and can exhibit excellent electrical performance.

[0044]

[0045] The appearance of a carbon material according to one embodiment of the present invention is as shown in Fig. 1.

[0046] In addition, the carbon material according to one embodiment of the present invention specifically has the following characteristics.

[0047] In one embodiment of the present invention, the pore distribution of the carbon material is such that the pore volume of pores having a pore diameter of 17 Å or less is 30% or less of the total pore volume. In other words, in one embodiment of the present invention, the pore distribution of the carbon material is such that the pore volume of pores having a pore diameter of greater than 17 Å is more than 70% of the total pore volume. More preferably, in one embodiment of the present invention, the pore distribution of the carbon material may be such that the pore volume of pores having a pore diameter of 17 Å or less is 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, or 24% or less of the total pore volume. In addition, the pore distribution of the carbon material according to one embodiment of the present invention may be such that the pore volume of pores having a pore diameter of 17 Å or less may be 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more of the total pore volume, or may be 0%.

[0048] At this time, the pore distribution of the carbon material according to one embodiment of the present invention may be such that the pore volume of the pores having a pore diameter of 17Å to 500Å among the pores having a pore diameter exceeding 17Å may be 70% or more, and the average pore diameter may be 20Å to 150Å, more preferably 50Å to 100Å.

[0049] In addition, the specific surface area of ​​the carbon material according to one embodiment of the present invention is 1 m 2 / g to 200m 2 / g is.

[0050] According to one embodiment of the present invention, the carbon material has an intensity ratio of the D peak to the G peak by Raman analysis, i.e., the D peak / G peak intensity ratio is 0.1 to 0.9, 0.2 to 0.8, 0.3 to 0.7, or 0.4 to 0.6, and the 2D peak / G peak intensity ratio is 0.5 to 1.5, 0.6 to 1.4, 0.7 to 1.3, 0.8 to 1.2, or 0.9 to 1.1.

[0051] The tap density of the carbon material according to one embodiment of the present invention may be 0.4 g / cm3 to 2.0 g / cm3, more preferably 0.6 g / cm3 to 1.2 g / cm3. Considering that the tap density of general commercial graphene is 0.05 g / cm3 to 0.2 g / cm3, the carbon material according to one embodiment of the present invention has a very high density. The tap density may mean the apparent density obtained by mechanically tapping a measuring container filled with powder.

[0052] The electrical conductivity of the carbon material according to one embodiment of the present invention is 61 to 76 S / cm, 63 to 74 S / cm, 65 to 72 S / cm, 67 to 70 S / cm, or 68 to 69 S / cm at 2,000 kgf.

[0053] According to one embodiment of the present invention, the carbon material may have a particle size distribution of 0.01 to 5 ㎛ in D10, 3.1 to 15 ㎛ in D50, and 8.1 to 50 ㎛ in D90. D10, D50, and D90 represent particle sizes corresponding to 10%, 50%, and 90%, respectively, when measuring particle size and accumulating volume from a small particle size, and are known units indicating the results analyzed through a particle size analyzer, and a further detailed description thereof will be omitted.

[0054] The content of carbon (C) in the carbon material according to one embodiment of the present invention may be 98 wt% or more, and more preferably 98.0 wt% or more, 98.1 wt% or more, 98.2 wt% or more, 98.3 wt% or more, 98.4 wt% or more, 98.5 wt% or more, 98.6 wt% or more, or 98.7 wt% or more.

[0055] Additionally, the content of oxygen (O) in the carbon material according to one embodiment of the present invention may be less than 2 wt%, and more preferably less than 2.0 wt%, less than 1.9 wt%, less than 1.8 wt%, less than 1.7 wt%, less than 1.6 wt%, less than 1.5 wt%, less than 1.4 wt%, less than 1.3 wt%, less than 1.2 wt%, or less than 1.1 wt%.

[0056] The impurity content included in the carbon material according to one embodiment of the present invention may be a total content of metals such as iron (Fe) and copper (Cu) of 100 ppm or less, and a total content of alkali metals such as sodium (Na) and calcium (Ca) of 20 ppm or less.

[0057]

[0058] Meanwhile, the carbon material for the electrode of the supercapacitor according to one embodiment of the present invention can be manufactured from biochar formed by carbonizing biomass.

[0059] The biomass may be a woody biomass, such as at least one of oak, red oak, rice straw, giant reed, sugarcane residue, corn residue, switchgrass, eucalyptus, poplar, palm residue, pine, and energy crops. Preferably, the biomass may be oak, red oak, or a mixture thereof.

[0060] Wood biomass can be processed from regular trees into wood pellets.

[0061] A method for manufacturing a carbon material for a supercapacitor according to one embodiment of the present invention may include (s1) a step of carbonizing biomass to manufacture biochar, (s2) a step of pulverizing the carbonized biochar, and (s3) a step of removing impurities from the pulverized biochar.

[0062] The step of carbonizing the biomass can be performed by introducing the biomass into a heating zone with different temperature ranges.

[0063] For example, the step of carbonizing biomass may include carbonization steps of 1 to 6, wherein step 1 may be performed at a temperature of 170°C to 200°C, step 2 may be performed at a temperature of 200°C to 280°C, step 3 may be performed at a temperature of 280°C to 500°C, step 4 may be performed at a temperature of 500°C to 700°C, step 5 may be performed at a temperature of 700°C to 800°C, and step 6 may be performed at a temperature of 800°C to 1,100°C, and may be performed for a total time of 3 to 60 minutes.

[0064] Carbonization is the process of heating organic matter to pyrolyze it into a carbon-rich substance. It can be performed while blocking the inflow of oxygen. This is a well-known process, so a more detailed description thereof will be omitted.

[0065] The biochar formed after carbonization has a carbon content of more than 98 wt% and becomes a high-density carbon material.

[0066] Typically, biomass contains approximately 50 wt% of organic compounds, including carbon (about 6 wt%), hydrogen (about 6 wt%), oxygen (about 44 wt%), inorganic matter (about 0.3 wt%), and nitrogen (about 0.1 wt%), and its chemical composition includes cellulose (about 40 to 45 wt%), hemicellulose (about 11 to 20 wt%), and lignin (about 20 to 30 wt%) in its cell walls.

[0067] In step 1, water vapor is generated from the surface of the biomass, and small amounts of carbon dioxide, acetic acid, etc. are produced.

[0068] In the second stage, steam, carbon dioxide, acetic acid, etc. may be generated within the biomass, and hemicellulose is decomposed. The temperature at which hemicellulose is decomposed may be 220°C to 260°C.

[0069] In step 3, cellulose is decomposed, and lignin is also decomposed. The temperature at which cellulose is decomposed may be between 240°C and 350°C, and the temperature at which lignin is decomposed may be between 280°C and 500°C.

[0070] When carbonizing under pressure conditions of 1.1 to 2 atm, lignin can volatilize into tar (TAR; total aerosol residue) at 370 to 500°C, and the volatilized tar can fill the micro-pores within the biochar generated during the carbonization process of biomass by impregnating them. Steps 4 and 5 can be performed to prevent this phenomenon by discharging volatile substances such as tar to the outside.

[0071] In stage 4, volatile substances such as tar begin to escape from the biomass.

[0072] In Step 5, all volatile substances can be emitted outside the biomass. However, some volatile substances may remain within the biomass. At this time, the emitted substances are captured outside the heating zone, and the captured volatile substances, such as tar, can be cooled, filtered, and separated to produce biodiesel, dio-water, and other products.

[0073] In step 6, a pyrolytic carbon coating (PCC) method can be applied to remove oxygen (O) and other substances formed on the surface of the biochar by applying heat to the carbon (C) component contained in hydrocarbon gases (CH) such as LNG and LPG. PCC refers to a method in which biochar is heated to the carbon (C) component contained in hydrocarbon gases (CH), thereby removing oxygen (O) and other substances formed on the surface of the biochar and simultaneously coating the carbon by combining the carbon with the remaining substances on the surface.

[0074] Biochar treated with PCC after tar removal has a reduced oxygen (O) content of less than 2 wt%, and carbon is bonded to some metals, such as iron and aluminum, contained within the biochar, making it electrochemically stable, exhibiting characteristics similar to, yet different from, commercial graphene. While single-layer carbon materials may be formed, typically, a layered carbon material with a small number of layers, such as 1.5, 2, 2.5, or 3 layers, is formed.

[0075] The step of crushing the carbonized biochar can be performed to ensure that biochar particles of various particle sizes have a predetermined particle size. The biochar can be crushed to have an average particle size of 1 μm to 100 μm. If the biochar has a particle size within this range, impurities in the biochar can be easily removed in subsequent processes.

[0076] The step of removing impurities from the pulverized biochar may include only a single impurity removal step, but it may be preferable to include multiple impurity removal steps.

[0077] The first impurity removal step can be performed to remove metal impurities such as iron (Fe) contained in the biochar, and can be performed, for example, by passing the biochar through a magnetic track at a constant flow rate of 1 m / min to 5 m / min.

[0078] Secondary and tertiary impurity removal steps may be performed to further remove more microscopic impurities, and may be performed by sequentially immersing the biochar in an acidic aqueous solution and a basic aqueous solution.

[0079] The secondary impurity removal step can be performed, for example, by immersing the biochar that has passed through the magnetic track in a 10 wt% to 50 wt% hydrochloric acid solution for 1 to 6 hours, then removing the hydrochloric acid component with distilled water in a volume of 200% to 5,000% of the 10 wt% to 50 wt% hydrochloric acid solution, filtering, and drying at a temperature of 60°C to 120°C. The type of acidic aqueous solution is not particularly limited, and various known acidic aqueous solutions other than the hydrochloric acid solution can be used.

[0080] In addition, the third impurity removal step can be performed by, for example, immersing biochar that has been washed with an acidic solution, neutralized with distilled water, and then dried in a 10 wt% to 50 wt% potassium hydroxide solution for 1 to 6 hours, then removing the potassium hydroxide component with distilled water in a volume of 200% to 5,000% of the 10 wt% to 50 wt% potassium hydroxide solution, filtering, and drying at a temperature of 60°C to 120°C. The type of alkaline aqueous solution is not particularly limited, and various known alkaline aqueous solutions other than the potassium hydroxide solution can be used.

[0081] Meanwhile, the secondary and tertiary impurity removal steps may be performed in reverse order, or only one of the two impurity removal steps may be performed. In other words, the biochar may be first immersed in an alkaline aqueous solution and then in an acidic aqueous solution. Alternatively, the biochar may be immersed in only one of the alkaline and acidic aqueous solutions.

[0082] Meanwhile, biochar contains various inorganic and metal components. These impurities can degrade the electrical properties of supercapacitors, so it's advisable to remove them after biochar production using alkaline and acidic treatments. These impurities can be removed using the aforementioned alkaline and acidic solutions.

[0083] The biochar manufactured through the above-described process exhibits characteristics similar to, yet different from, commercial graphene, and has characteristics suitable for use as an electrode material for supercapacitors.

[0084]

[0085] Meanwhile, another embodiment of the present invention provides an electrode of a supercapacitor and a supercapacitor including a carbon material according to the present disclosure.

[0086] However, the carbon material according to the present disclosure may also be used as an electrode of a supercapacitor and an electrode of an electric energy storage device other than a supercapacitor and an electric energy storage device.

[0087] According to another embodiment of the present invention, an electrode of a supercapacitor can be manufactured by coating an electrode composition including a carbon material and a binder according to the present disclosure on the surface of a current collector, drying the coated electrode body, and then press-molding it.

[0088] After drying the electrode body, the density of the electrode of the press-molded supercapacitor is 0.65 g / cm 3 1.35g / cm 3 It could be.

[0089] The binder may include a plurality of binders, for example a first binder and a second binder.

[0090] As the first binder, polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene, vinylidene fluoride copolymer, tetrafluoroethylene-perfluoroalkylene vinyl ether copolymer, etc. can be used, and polytetrafluoroethylene can be preferably used in terms of chemical stability.

[0091] Additionally, SBR (Styrene Butadiene Rubber), BM400B (Zeon) etc. can be used as a second binder.

[0092] However, depending on the need, only one binder may be used, for example, only the first binder or the second binder may be used.

[0093] A carbon material according to one embodiment of the present invention has very high electrical conductivity characteristics, and when used as an electrode material of a supercapacitor, a supercapacitor exhibiting high output characteristics due to low resistance characteristics can be provided.

[0094]

[0095] Hereinafter, the present invention will be described in more detail through manufacturing examples, examples, and comparative examples.

[0096] The following examples are supercapacitors that include carbon materials manufactured according to a manufacturing example according to one embodiment of the present invention as electrode materials, and the comparative examples are supercapacitors that include activated carbon having a particle size distribution and composition ratio different from those of the examples as electrode materials.

[0097] In order to improve the accuracy of comparison and reliability of the test, the following examples and comparative examples were produced by manufacturing sample electrodes through the same manufacturing process to manufacture supercapacitors of the same structure, and then the electrode surface resistance and electrostatic resistance (ESR) of each supercapacitor were measured. AC ), leakage current (LC), and electrostatic resistance (ESR) DC ), electrostatic capacity (CAP) and specific capacity were confirmed.

[0098] Meanwhile, the following manufacturing examples and examples are merely for explaining the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace the following manufacturing examples and examples at the time of filing this application.

[0099]

[0100] Manufacturing example

[0101] According to the steps (s1) to (s3) described above, a carbon material was manufactured from biochar formed by carbonizing oak as biomass. In this case, in step (s1), all of the carbonization steps 1 to 6 described above were performed, in step (s2), the biochar was pulverized using a ball mill, and in step (s3), all of the first to third impurity removal steps described above were performed.

[0102] In the carbon material manufactured according to the manufacturing example, the pore volume of pores having a pore diameter of 17 Å or less was measured to be 23.39% of the total pore volume.

[0103] In addition, the specific surface area of ​​the carbon material manufactured according to the manufacturing example is 62.55 m 2 / g, and the particle size distribution was 3.4㎛ at D10, 5.9㎛ at D50, and 9.1㎛ at D90.

[0104] Additionally, the tap density of the carbon material manufactured according to the manufacturing example was 1.6 g / cm3.

[0105] Referring to Fig. 4, the D peak / G peak intensity ratio and the 2D peak / G peak intensity ratio measured by Raman analysis of the carbon material manufactured according to the manufacturing example were 0.49 and 1.045, respectively, indicating that it has a single or several layered structure. On the other hand, referring to Fig. 5, the D peak / G peak intensity ratio and the 2D peak / G peak intensity ratio measured by Raman analysis of commonly sold commercial graphene were 1.16 and 0.32, respectively, indicating that it has strong crystallinity and a single or more (or several) layered structure.

[0106] Referring to Fig. 6, the electrical conductivity of the carbon material manufactured according to the manufacturing example showed a value of 68.687 S / cm at 2,000.5 kgf. On the other hand, referring to Fig. 7, the electrical conductivity of activated carbon (YP-50, Kuraray), which is commonly used as an electrode material for supercapacitors, showed a value of 5.384 S / cm at 1,999 kgf, which can be seen to be 10% or less lower than the electrical conductivity of the carbon material manufactured according to the manufacturing example.

[0107] In addition, as can be seen from the TEM analysis results in FIGS. 8 to 11 and Table 1 below, the carbon (C) content in the carbon material manufactured according to the manufacturing example of the present invention was measured to be 98.72 wt%, and the oxygen (O) content was measured to be 1.09 wt%.

[0108] Elemental Weight Ratio (wt%) wt% Sigma Elemental Ratio (Atomic %) C98.720.0699.1N000O1.090.060.82Na000Si0.180.020.08S000 Total:100 100

[0109] Table 1: TEM analysis results of carbon materials according to the manufacturing example of the present invention.

[0110] Example

[0111] 95.0 wt% of carbon material manufactured according to the manufacturing example was placed in a container, and a solution of 0.5 wt% carboxymethyl cellulose (CMC) dissolved in distilled water as a dispersing agent was added thereto in the same volume as the carbon material, and then the carbon material was first dispersed using a dispersing stirrer to prepare a slurry.

[0112] 3.5 wt% of polytetrafluoroethylene (PTFE) as a binder and 1.0 wt% of SBR (Styrene Butadiene Rubber) were added to the primary dispersion slurry, and the electrode material was mixed by dispersion stirring.

[0113] Afterwards, a small amount of distilled water was added as a dispersing medium and stirred at low speed until a solid state with a viscosity of 20,000 cp was obtained, thereby obtaining a conductive solid electrode slurry. At this time, when the solid state reached one monomer, the addition of the dispersing medium was stopped.

[0114] A conductive solid electrode slurry was coated to a thickness of 70 μm on a cross-section of a 20 μm thick aluminum etching foil, dried, and then a compression molding process was performed in a roll press heated to 80°C to produce a sheet-shaped electrode having a thickness of 50 μm and an electrode density of 0.91 g / cm3.

[0115] The carbon material electrode manufactured in this manner was cut to 100.0 mm in width and 100.0 mm in length, and an aluminum terminal was ultrasonically welded to the surface of each electrode to bond it.

[0116] In order to prevent electrical shorts between the two electrodes and to ensure smooth flow of the impregnated electrolyte, a porous non-woven fabric separator was cut to 120.0 mm in width and 120.0 mm in length between each electrode to which aluminum terminals were welded, and then positioned in the center and inserted into an aluminum pouch. Then, a 0.1 N concentration organic electrolyte containing acetonitrile as a solvent and tetraethyl ammonium tetrafluoroborate (TEABF4) as a solute was impregnated onto the surfaces of the two electrodes, and the aluminum pouch was sealed by heat compression, thereby manufacturing a test pouch cell including the first to fifth specimen electrodes.

[0117] For five types of supercapacitors including the first to fifth specimen electrodes manufactured according to the example, a test was conducted under the conditions that the charging voltage was 2.7 V, the charging current was the same as the discharge current, the charging time was 1 hour after the charging voltage reached 2.7 V, and the discharge current was 0.1 A. At this time, the electrode surface resistance, the alternating current resistance (ESR) AC ), leakage current (LC), and electrostatic resistance (ESR)DC ), electrostatic capacity (CAP) and specific capacity were evaluated, and the results are shown in Table 2 below.

[0118] Electrode surface resistance ESR AC LCESR DC CAP(Ω / sqm)(mΩ)(㎃)(mΩ)(F)33130.9896.8

[0119] Table 2: Electrical characteristics of a supercapacitor using a carbon material electrode according to the present invention (0.1 A discharge)

[0120] In addition, the electrostatic capacity measured at discharge currents of 0.1 A, 0.5 A, 1.0 A, 2.0 A, and 5.0 A is shown in Table 3 below.

[0121]

[0122] Discharge current (A) 0.1 0.5 1.0 2.0 5.0 Capacitance (F) 6.8 6.0 4.7 3.3 1.8

[0123] Table 3: Electrical characteristics of supercapacitors by discharge current

[0124] Meanwhile, in order to increase the power density of the supercapacitor, it is advantageous to set the DC resistance standard to 100 mΩ or less at a temperature of 25°C.

[0125] In an example in which the carbon material electrode of the present invention was applied, the DC resistance was found to be 100 mΩ or less, which proves that high output of the supercapacitor according to the example is possible.

[0126]

[0127] Comparative Example 1

[0128] A sheet-like electrode was manufactured in the same manner as in Example 1, except that a mixture of 90.0 wt% of amorphous coconut shell-based carbonized activated carbon (YP-50, specific surface area 1,344 m2 / g, pore distribution: 86% of the total pore volume of pores with a diameter of 17 Å or less) and 5.0 wt% of the conductivity modifier Super P was used instead of the carbon material of Example 1. The density of the electrode was 0.60 g / cm3. Thereafter, a test pouch cell including the first to fifth specimen electrodes was manufactured in the same manner as in Example 1.

[0129] For five types of supercapacitors including the first to fifth specimen electrodes manufactured according to Comparative Example 1, the electrode surface resistance and alternating current resistance (ESR) were measured in the same manner as in Example 1. AC ), leakage current (LC), and electrostatic resistance (ESR) DC ), electrostatic capacity (CAP) and specific capacity were evaluated, and the results are shown in Table 4 below.

[0130] Electrode surface resistance ESR AC LCESR DC CAP(Ω / sqm)(mΩ)(㎃)(mΩ)(F)7803602.341012.5

[0131] Table 4: Electrical characteristics of a supercapacitor using activated carbon (YP-50) electrodes (0.1 A discharge) Also, the electrostatic capacity measured at discharge currents of 0.1 A, 0.5 A, 1.0 A, 2.0 A, and 5.0 A is shown in Table 5 below.

[0132] Discharge current (A) 0.1 0.5 125 Capacitance (F) 12.5 7.8 3.2 0.50

[0133] Table 5: Electrical characteristics of supercapacitors by discharge current

[0134] Referring to Table 4, the electrostatic capacity of the supercapacitor according to the embodiment is small, at about 50% of the electrostatic capacity of the supercapacitor according to Comparative Example 1 using an activated carbon (YP-50) electrode.

[0135] However, referring to Table 5, it can be seen that the capacity retention rate in the example is better than that in comparative example 1 as the discharge current is increased. This is understood to be because the example has excellent direct current resistance and smooth pore penetration of large solvent molecules and movement of ions.

[0136] From the BET analysis results, the specific surface area of ​​the carbon material according to the present invention is 62.55 m 2 / g and the specific surface area of ​​activated carbon (YP-50) is 1,344 m 2 / g, the fact that the electrostatic capacity of the carbon material is about 50% of that of activated carbon proves that the pore distribution according to the present invention directly affects the electrostatic capacity and the capacity retention rate during high current discharge.

[0137]

[0138] Comparative Example 2

[0139] A sheet-like electrode was manufactured in the same manner as in Example 1, except that a mixture of 90.0 wt% of amorphous coke-based carbonized activated carbon (CEP-21KS, specific surface area 2,000 m2 / g, pore distribution: 72% of the total pore volume of pores with a diameter of 17 Å or less) and 5.0 wt% of the conductivity modifier Super P was used instead of the carbon material of Example 1. The density of the electrode was 0.65 g / cm3.

[0140] Afterwards, test pouch cells including the first to fifth specimen electrodes were manufactured in the same manner as in Example 1. For five types of supercapacitors including the first to fifth specimen electrodes manufactured according to Comparative Example 2, electrode surface resistance and alternating current resistance (ESR) were measured in the same manner as in Example 1. AC ), leakage current (LC), and electrostatic resistance (ESR) DC ), electrostatic capacity (CAP) and specific capacity were evaluated, and the results are shown in Table 4 below.

[0141] Electrode surface resistance ESR ACLCESR DC CAP(Ω / sqm)(mΩ)(㎃)(mΩ)(F)5952972.335014.5

[0142] Table 6: Electrical characteristics of a supercapacitor using activated carbon (CEP-21KS) electrodes (0.1 A discharge)

[0143] In addition, the electrostatic capacity measured at discharge currents of 0.1 A, 0.5 A, 1.0 A, 2.0 A, and 5.0 A is shown in Table 7 below.

[0144] Discharge current (A) 0.1 0.5 125 Capacitance (F) 14.5 8.9 5.2 1.30

[0145] Table 7: Electrical characteristics of supercapacitors by discharge current

[0146] Referring to Table 6, the electrostatic capacity of the supercapacitor according to the embodiment is less than 50% of the electrostatic capacity of the supercapacitor according to Comparative Example 2 using an activated carbon (CEP-21KS) electrode.

[0147] However, referring to Table 7, it can be seen that the capacity retention rate in the example is better than that in comparative example 2 when the discharge current is high. This is understood to be because the example has excellent direct current resistance and smooth pore penetration of large solvent molecules and movement of ions.

[0148] From the BET analysis results, the specific surface area of ​​the carbon material according to the present invention is 62.55 m 2 / g and the specific surface area of ​​activated carbon (CEP-21KS) is 2,000 m 2 / g, the fact that the electrostatic capacity of the carbon material is about 50% of that of activated carbon proves that the pore distribution according to the present invention directly affects the electrostatic capacity and the capacity retention rate during high current discharge.

[0149]

[0150] Comparative Example 3

[0151] A sheet-like electrode was manufactured in the same manner as in Example 1, except that a mixture of 90.0 wt% of amorphous phenolic resin-based carbonized activated carbon (MSP-20, specific surface area 2,750 m2 / g, pore distribution: 82% of the total pore volume of pores with a diameter of 17 Å or less) and 5.0 wt% of the conductivity modifier Super P was used. The density of the electrode was 0.66 g / cm3.

[0152] Afterwards, test pouch cells including the first to fifth specimen electrodes were manufactured in the same manner as in Example 1. For five types of supercapacitors including the first to fifth specimen electrodes manufactured according to Comparative Example 3, electrode surface resistance and alternating current resistance (ESR) were measured in the same manner as in Example 1. AC ), leakage current (LC), and electrostatic resistance (ESR) DC ), electrostatic capacity (CAP) and specific capacity were evaluated, and the results are shown in Table 4 below.

[0153] Electrode surface resistance ESR AC LCESR DC CAP(Ω / sqm)(mΩ)(㎃)(mΩ)(F)5032742.032214.8

[0154] Table 8: Electrical characteristics of supercapacitors using activated carbon (MSP-20) electrodes (0.1 A discharge)

[0155] In addition, the electrostatic capacity measured at discharge currents of 0.1 A, 0.5 A, 1.0 A, 2.0 A, and 5.0 A is shown in Table 9 below.

[0156] Discharge current (A) 0.1 0.5 125 Capacitance (F) 14.8 8.9 5.4 2.0 0.3

[0157] Table 9: Electrical characteristics of supercapacitors by discharge current

[0158] Referring to Table 8, the electrostatic capacity of the supercapacitor according to the embodiment is less than 50% of the electrostatic capacity of the supercapacitor according to Comparative Example 3 using an activated carbon (MSP-20) electrode.

[0159] However, referring to Table 9, it can be seen that the capacity retention rate in the example is better than that in comparative example 3 when the discharge current is high. This is understood to be because the example has excellent direct current resistance and smooth pore penetration of large solvent molecules and movement of ions.

[0160] From the BET analysis results, the specific surface area of ​​the carbon material according to the present invention is 62.55 m 2 / g and the specific surface area of ​​activated carbon (MSP-20) is 2,750 m 2 / g, the fact that the electrostatic capacity of the carbon material is about 50% of that of activated carbon proves that the pore distribution according to the present invention directly affects the electrostatic capacity and the capacity retention rate during high current discharge.

[0161]

[0162] The outputs of each of Examples, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are as shown in Table 10 below.

[0163] At this time, the output is calculated using the following function.

[0164] P = V 2 / (4*ESR DC )

[0165] Here, P is power output, V is voltage, and ESR DC is the DC resistance, and the unit of output is W.

[0166]

[0167] Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Output (W) 20.47 4.44 5.20 5.65

[0168] Table 10: Output of each of Example, Comparative Example 1, Comparative Example 2, and Comparative Example 3

[0169] The power density divided by the weight of each manufactured electrode of Examples, Comparative Examples 1, 2, and 3 is as shown in Table 11 below.

[0170]

[0171] Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Weight of electrode (g) 0.9 1 0.6 0.65 0.66 Power density (kW / kg) 22.5 0 7.4 0 8.0 1 8.57

[0172] Table 11: Power density of each of Examples, Comparative Example 1, Comparative Example 2, and Comparative Example 3

[0173] It can be seen that the supercapacitor according to the embodiment using the carbon material of the present invention as an electrode exhibits characteristics of higher output and output density than the supercapacitor according to the comparative example using activated carbon as an electrode.

[0174]

[0175] While one embodiment of the present invention has been exemplified above, it is not intended to limit the scope of the present invention to the aforementioned embodiments. Those skilled in the art will be able to appropriately modify one embodiment of the present invention, including omitting, modifying, or replacing all or part of the configuration of the present invention, or adding other configurations, without departing from the technical spirit of the present invention, by referring to this specification and the attached drawings.

[0176] The terms and expressions in this specification should be interpreted broadly and not in a restrictive sense. As used herein, the term "includes" does not exclude the presence or addition of one or more other components other than the mentioned components. Furthermore, as used herein, the term "to" includes upper and lower limits. For example, "1 to 10" includes the upper limit of 10 and the lower limit of 1, and can also be expressed as "1 or more and 10 or less."

[0177] Each of the embodiments exemplarily described herein can be combined with one another, and unless contradictory, the content described in a particular embodiment can be equally applied to other embodiments even if not described in the other embodiments.

Claims

1. It has multiple pores, Among the above multiple pores, the pore volume of the pores having a pore diameter of 17Å or less is 30% or less of the total pore volume. Carbon material for electrodes of supercapacitors.

2. In paragraph 1, The above carbon material is manufactured from biochar formed by carbonizing biomass. Carbon material for electrodes of supercapacitors.

3. In paragraph 1, The above carbon material has a carbon (C) content of 98 wt% or more and an oxygen (O) content of less than 2 wt%. Carbon material for electrodes of supercapacitors.

4. In paragraph 1, The above carbon material has a D peak / G peak intensity ratio of 0.1 to 0.9 and a 2D peak / G peak intensity ratio of 0.5 to 1.5 as determined by Raman analysis. Carbon material for electrodes of supercapacitors.

5. In paragraph 1, The above carbon material has a tap density of 0.4 g / cm3 or more and 2.0 g / cm3 or less. Carbon material for electrodes of supercapacitors.

6. In paragraph 1, The above carbon material has an electrical conductivity of 61 S / cm to 76 S / cm at 2,000 kgf. Carbon material for electrodes of supercapacitors.

7. In paragraph 1, The above carbon material is D 10 1 to 5㎛, D 50 10 to 15㎛, D 90 having a particle size distribution of 8.1 to 50㎛, Carbon material for electrodes of supercapacitors.

8. In paragraph 1, The above carbon material has a specific surface area of ​​1 m 2 / g to 200m 2 / g person, Carbon material for electrodes of supercapacitors.

9. In paragraph 1, The above carbon material has a total metal content of 100 ppm or less, The total content of alkali metals is less than 20 ppm, Carbon material for electrodes of supercapacitors.

10. Containing a carbon material for electrode of a supercapacitor according to Article 1, Electrodes of a supercapacitor.

11. In paragraph 10, The above electrode has a density of 0.65 g / cm 3 1.35g / cm 3 person, Electrodes of a supercapacitor.

12. Containing the electrode of the super capacitor according to Article 10, Supercapacitor.

13. A step of producing biochar by carbonizing biomass; A step of crushing the carbonized biochar; and A step of removing impurities from the above-mentioned pulverized biochar; comprising; Method for manufacturing carbon material for electrode of supercapacitor.

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