Complex for electrode of supercapacitor, electrode of supercapacitor and supercapacitor including same

Abstract

In one embodiment, the present invention provides a carbon material-activated carbon composite comprising a carbon material and activated carbon, wherein the pore volume of the pores having a pore diameter of 17 Å or less is 30% or less of the total pore volume, an electrode of a supercapacitor comprising the same, and a supercapacitor.

Description

Technology Field

[0001] The present disclosure relates to a composite for electrodes of a supercapacitor, an electrode of a supercapacitor comprising the same, and a supercapacitor, and more specifically, to a low DC resistance (ESR DC The present invention relates to a composite for electrodes of a supercapacitor for providing a supercapacitor having the characteristics of high power density, high electrode density and high energy density, an electrode of a supercapacitor including the same, and a supercapacitor. Background Technology

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

[0004] In particular, supercapacitors provide the high-output energy required for the rapid acceleration of electric vehicles and can recover instantaneously generated energy to supplement the battery used as the primary power source for driving, thereby enabling the commercial operation of electric vehicles.

[0005] Supercapacitors must store sufficient energy to provide the energy required for driving, and to effectively manage the associated costs, volume, and weight, they require very high power density per volume and per weight, a long lifespan, and low cost.

[0006] Furthermore, due to their performance and characteristics, the application of supercapacitors as electronic components in the electronics industry is also on the rise.

[0007] As the power consumption of semiconductors such as complementary metal oxide semiconductors (CMOS), which are commonly used in various electronic equipment or devices, is minimized, supercapacitors with a capacitance of 1 Farad are attracting attention as memory backup applications because they can replace nickel-cadmium or lithium batteries and provide backup power for several months.

[0008] Compared to conventional electrolytic capacitors, polymer capacitors, tantalum capacitors, etc., supercapacitors use porous activated carbon-based electrodes to form a large effective specific surface area and store 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 conventional capacitors).

[0009] Supercapacitors provide high capacitance through the formation of an electric double layer at the interface between electrode materials with a high specific surface area, typically activated carbon, and the electrolyte.

[0010] Supercapacitors provide high capacitance through the formation of an electric double layer at the interface between electrode materials with a high specific surface area, typically activated carbon, and the electrolyte, and it is known that capacitance is directly proportional to the specific surface area of ​​the electrode material.

[0011] However, there are also technical problems related to supercapacitors at present.

[0012] In general, the experimentally measured capacitance of a supercapacitor based on an activated carbon electrode is much smaller than the theoretical capacitance calculated from the analyzed specific surface area and the width of the dipole layer.

[0013] In activated carbon with a very high specific surface area, the measured capacity is less than about 20% of the theoretical capacity, and this result is related to the presence of micropores (less than 2 nm), which have a wetting deficiency where the electrolyte cannot access some of the pores, and the electric double layer cannot be successfully formed in pores spaced about 1 nm to 2 nm (10 Å to 20 Å) apart from the charged surface.

[0014] In addition, depending on the carbon source and heat treatment temperature, a large portion of the surface of the activated carbon may take the form of micropores that are inaccessible to the liquid electrolyte.

[0015] Despite having high theoretical capacity at the electrode level, activated carbon electrodes cannot provide energy storage devices with massive capacity at the supercapacitor cell or pack level.

[0016] Meanwhile, much research is also being conducted to develop electrode materials with enhanced capacity per unit volume using porous carbon-based materials such as graphene, carbon nanotube (CNT)-based composites, porous graphite oxide, and porous meso carbon.

[0017] Among these, graphene materials have recently been attracting attention for exhibiting characteristics such as high thermal conductivity, high electrical conductivity, high strength, and a high specific surface area.

[0018] A single graphene sheet has an external specific surface area of ​​approximately 2,675 m² / g, in contrast to the external specific surface area of ​​approximately 1,300 m² / g provided by the corresponding single-walled CNT (the internal surface is inaccessible to the electrolyte, while the external surface is accessible to the liquid electrolyte). Additionally, the electrical conductivity of graphene is higher than that of CNT.

[0019] However, individual graphene sheets have a strong tendency to self-restacking, which reduces the specific surface area accessible to the electrolyte at the electrodes of the supercapacitor.

[0020] Even if individual graphene sheets are partially re-stacked, it is desirable that the resulting multilayer structure still possesses interlayer voids of an appropriate size. Furthermore, the voids must be large enough to allow the electrolyte to access and for electric double layer charges to form.

[0021] However, the gaps between pores or graphene must be sufficiently small to ensure a large tap density. The tap density of graphene-based electrodes manufactured by conventional processes is typically less than 0.3 g / cm³, more typically less than 0.2 g / cm³.

[0022] To a significant extent, the requirements for large void size and high porosity levels and the requirements for high tap density are mutually exclusive in supercapacitors.

[0023] In addition, the manufacturing process required to meet the above conditions is very complex and the yield is very low, which causes the price of graphene to rise and makes graphene unsuitable for use as an electrode material for supercapacitors.

[0024] Another major technical problem regarding the use of graphene sheets as electrode active materials for supercapacitors is forming a thick layer of active material on the surface of a solid current collector (e.g., Al foil) using a conventional graphene-solvent slurry coating process.

[0025] Relatively thick electrodes tend to break easily or be structurally incomplete, and large amounts of binder resin are used to address this; this issue is exacerbated in the case of electrodes manufactured using graphene as the main material.

[0026] It is not easy to produce graphene-based electrodes that are thick and maintain high porosity, ensuring that they have pores fully accessible to the liquid electrolyte and secure sufficient ion storage space. Furthermore, low areal density and low volume density lead to problems such as low capacitance per volume and low energy density per volume in supercapacitors.

[0027] In addition, there is a need to overcome problems such as the re-stacking of graphene sheets, the requirement for a large proportion of binder resin, and the difficulty of creating thick graphene electrode layers.

[0028] Accordingly, there is a need for an active material with a high mass load (areal density) and high apparent density (high tap density), and a supercapacitor with a thick electrode thickness, high capacitance, high energy density, and high power density without significantly reducing electron and ion transport rates. Prior art literature

[0030] Republic of Korea Published Patent No. 10-2021-0149993 (December 10, 2021) The problem to be solved

[0031] One of the objectives of the present invention is to provide a composite for electrodes of a supercapacitor to provide a supercapacitor having low DC resistance, high power density, high electrode density, and excellent capacitance (energy density) per unit volume. means of solving the problem

[0033] In one embodiment, the present invention provides a composite for an electrode of a supercapacitor comprising a carbon material and activated carbon, wherein the pore volume of the pores having an optimal diameter range in which solvent molecules of the electrolyte can sufficiently penetrate is 30% or less of the total pore volume, and an electrode of a supercapacitor comprising the same and a supercapacitor. Effects of the invention

[0035] The present invention can provide a composite for electrodes of a supercapacitor to provide a supercapacitor having low DC resistance, high power density, high electrode density, and excellent capacitance (energy density) per unit volume as one effect. Brief explanation of the drawing

[0037] Figure 1 shows a carbon material manufactured according to a manufacturing example of the present invention. Figure 2 shows the BET analysis results of a carbon material prepared according to a manufacturing example of the present invention. Figure 3 shows the BET analysis results of commercial activated carbon (YP-50). Figure 4 shows the Raman spectrum of a carbon material prepared according to the manufacturing example of the present invention. Figure 5 shows the Raman spectrum of commercial graphene. Figure 6 shows the electrical conductivity measurement results of a carbon material manufactured according to a manufacturing example of the present invention. Figure 7 shows the electrical conductivity measurement results of commercial activated carbon (YP-50). FIGS. 8 to 11 show the TEM analysis results of a carbon material prepared according to the manufacturing example of the present invention. FIG. 12 shows the particle size distribution curve of a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention before grinding. FIG. 13 shows an SEM image of a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention before grinding. FIG. 14 shows the particle size distribution curve after grinding of a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention. FIG. 15 shows an SEM image of a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention after grinding. Specific details for implementing the invention

[0038] The present invention will be described in detail below with reference to the attached drawings. However, it should be noted in advance that the present invention is not limited to the contents described in this specification or the attached drawings. Those skilled in the art may implement the present invention in various forms without departing from the technical spirit of the invention by referring to the contents described in this specification and the attached drawings, and such implementations should also be understood as falling within the scope of the rights of the present invention.

[0040] A composite for an electrode of a supercapacitor according to one embodiment of the present invention comprises a carbon material and activated carbon having the following characteristics.

[0042] In one embodiment of the present invention, the pore distribution of the carbon material included in the electrode composite of a supercapacitor has a pore volume of pores with a pore diameter of 17 Å or less that is 30% or less of the total pore volume. More preferably, in one embodiment of the present invention, the pore distribution of the carbon material included in the electrode composite of a supercapacitor may have a pore volume of pores with a pore diameter of 17 Å or less that 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, in one embodiment of the present invention, the pore distribution of the carbon material included in the electrode composite of a supercapacitor may have a pore volume of pores with a pore diameter of 17 Å or less that is 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 it may be 0%.

[0043] At this time, the pore distribution of the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention may have a pore volume of 17 Å to 500 Å with a pore diameter exceeding 17 Å that is 70% or more, and the average pore diameter may be 20 Å to 150 Å, more preferably 50 Å to 100 Å.

[0044] In this specification, the crystal structure of the carbon material is similar in structure to graphite crystals, with planes arranged at equal intervals parallel to each other, but it consists of an imperfect amorphous structure in which the layers are stacked irregularly. In this crystal structure, countless nanometer-sized spaces are formed, and in this specification, these spaces are referred to as pores. Pores are classified into three stages according to their size: macropores, mesopores, and micropores, and pores of all stages and sizes exist.

[0045] In this specification, "work volume" means the total volume of all workpieces.

[0046] In addition, the specific surface area of ​​the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention is 1 m² 2 / g to 200m 2 / g is.

[0047] The carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention has an intensity ratio of the D peak to the G peak by Raman analysis, i.e., the D peak / G peak intensity ratio, of 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.

[0048] The tap density of the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention is 0.4 g / cm³ to 2.0 g / cm³, and 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 included in the electrode composite of a supercapacitor according to one embodiment of the present invention has a very high density. Tap density may refer to the apparent density obtained by mechanically tapping a measuring container filled with powder.

[0049] The electrical conductivity of the carbon material included in the electrode composite of a supercapacitor 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. In addition, the electrical conductivity of the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention is 14 to 17 S / cm, 14.5 to 16.5 S / cm, 15 to 16 S / cm, 15.2 to 15.8 S / cm, or 15.4 to 15.6 S / cm at 200 kgf.

[0050] The carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention may have a particle size distribution of 0.01 to 5 μm at D10, 3.1 to 15 μm at D50, and 8.1 to 50 μm at D90. D10, D50, and D90 represent particle sizes corresponding to 10%, 50%, and 90%, respectively, when the volume is accumulated starting from the smallest particle size by measuring the particle size, and represent known units indicating the results analyzed through a particle size analyzer, and further detailed explanation thereof is omitted.

[0051] In a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention, the carbon (C) content 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.

[0052] In addition, the oxygen (O) content in the carbon material included in the electrode composite of a supercapacitor 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%.

[0053] The impurity content included in the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention may be such that the total content of metals such as iron (Fe) and copper (Cu) is 100 ppm or less, and the total content of alkali metals such as sodium (Na) and calcium (Ca) is 20 ppm or less.

[0055] Meanwhile, the carbon material included in the electrode composite of a supercapacitor according to one embodiment of the present invention can be manufactured from biochar formed by carbonizing biomass.

[0056] The biomass may be woody biomass, for example, at least one of oak, red oak, rice straw, giant miscanthus, sugarcane byproduct, corn byproduct, switchgrass, eucalyptus, poplar, palm byproduct, pine, and energy crops. Preferably, the biomass may be oak, red oak, or a mixture thereof.

[0057] Woody biomass may be ordinary wood processed into wood pellets.

[0058] A method for manufacturing a carbon material included in a composite electrode for a supercapacitor according to one embodiment of the present invention may include (s1) a step of carbonizing biomass to produce biochar, (s2) a step of crushing the carbonized biochar, and (s3) a step of removing impurities from the crushed biochar.

[0059] The step of carbonizing biomass can be performed by introducing the biomass into heating zones of different temperature ranges.

[0060] For example, the step of carbonizing biomass may include 1 to 6 carbonization steps, and the 1st step may be performed at a temperature of 170°C to 200°C, the 2nd step at 200°C to 280°C, the 3rd step at 280°C to 500°C, the 4th step at 500°C to 700°C, the 5th step at 700°C to 800°C, and the 6th step at 800°C to 1,100°C, and may be performed for a total of 3 to 60 minutes.

[0061] Carbonization is a process of heating organic matter to induce pyrolysis, thereby converting it into a carbon-rich substance; this can be performed while blocking the influx of oxygen. As this is a known process, a more detailed description thereof is omitted.

[0062] Biochar formed after carbonization has a carbon content of 98 wt% or more and becomes a high-density carbon material.

[0063] At this time, a single-layer carbon material may be formed, but generally, a layered carbon material having a small number of layers, such as 1.5 layers, 2 layers, 2.5 layers, or 3 layers, is formed.

[0064] The step of grinding carbonized biochar can be performed to ensure that biochar particles having various particle sizes have a predetermined particle size. Biochar can be ground so that the average particle size is 1 µm to 100 µm, and specific methods for grinding biochar can apply various technologies without limitation, such as commonly used ball mills and blade mixers.

[0065] The step of removing impurities from the crushed biochar may include only a single impurity removal step, but it may be preferable to include multiple impurity removal steps.

[0066] The first impurity removal step can be performed to remove metal impurities such as iron (Fe) contained in the biochar, for example, by passing the biochar through a magnetic track at a constant flow rate of 1 m / min to 5 m / min.

[0067] Second and third impurity removal steps can be performed to further remove more microscopic impurities, and can be performed by sequentially immersing the biochar in an acidic aqueous solution and a basic aqueous solution.

[0068] The second impurity removal step can be performed, for example, by immersing the biochar that has passed through a magnetic track in a 10 wt% to 50 wt% hydrochloric acid solution for 1 to 6 hours, removing the hydrochloric acid component with 200% to 5,000% of the volume of the 10 wt% to 50 wt% hydrochloric acid solution using distilled water, 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 hydrochloric acid solutions may be used.

[0069] In addition, the third impurity removal step can be performed by, for example, washing with an acidic solution, neutralizing with distilled water, and then drying the biochar, immersing it in a 10 wt% to 50 wt% potassium hydroxide solution for 1 to 6 hours, removing the potassium hydroxide component with 200% to 5,000% of the volume of the 10 wt% to 50 wt% potassium hydroxide solution in distilled water, filtering, and drying at a temperature of 60°C to 120°C. The type of basic aqueous solution is not particularly limited, and various known basic aqueous solutions other than potassium hydroxide solution may be used.

[0070] The biochar produced through the aforementioned process exhibits characteristics similar to but different from commercial graphene, and possesses properties suitable for use as an electrode material for supercapacitors.

[0072] The activated carbon may be at least one of coconut shell-based activated carbon, phenol resin-based activated carbon, and coke pitch-based activated carbon, but is not limited thereto.

[0074] In a composite for an electrode of a supercapacitor according to one embodiment of the present invention, the carbon material and the activated carbon may exist in a weight ratio of 1:0.1 to 1 (carbon material:activated carbon), preferably 1:0.2 to 0.8 (carbon material:activated carbon), and more preferably 1:0.3 to 0.55 (carbon material:activated carbon). If the weight ratio of the activated carbon exceeds the aforementioned range, the distribution range of micropores having a diameter of less than 2 nm increases, making it difficult for the electrolyte to access the pores, and characteristics such as increased resistance, decreased electrode density, and decreased capacitance may appear. On the other hand, if the weight ratio of the activated carbon is below the aforementioned range, negative effects such as high output but low capacitance may appear. Therefore, it is advantageous to control the weight ratio of the activated carbon within the aforementioned range.

[0076] Carbon materials and activated carbon may be included in an amount of 79 wt% to 95 wt% based on the total weight of the composite for the electrode of a supercapacitor. If the content of carbon materials and activated carbon is less than the aforementioned range, there may be a negative effect of increased resistance, and if it exceeds the aforementioned range, there may be a negative effect of decreased electrode strength.

[0078] In addition, the electrode composite of a supercapacitor according to one embodiment of the present invention may further include a conductive additive. The conductive additive may be included in an amount of 2 wt% to 9 wt% based on the total weight of the electrode composite of the supercapacitor. The conductive additive may be used as an additive material in the electrode composition to complement the low electrical conductivity in the lateral aspect, which is a characteristic similar to graphene of the carbon material, and the low electrical conductivity and high resistance characteristics of activated carbon. As the conductive additive, a carbon black such as Ketjen black, acetylene black, or Super-P, mixed in a single or multiple manner, may be used.

[0080] In addition, the electrode composite of a supercapacitor according to one embodiment of the present invention may further include a binder. The binder may be included in an amount of 3 wt% to 12 wt% based on the total weight of the electrode composite of the supercapacitor. In addition, at least one of a rubber-based binder such as SBR (styrene butadiene rubber), an elastomer-based binder such as BM400B, or a Teflon-based binder such as polytetrafluoroethylene may be used as the binder.

[0082] The electrode composite of a supercapacitor according to the present invention can be manufactured through a manufacturing method comprising the following steps to increase electrode density.

[0083] (a1) A step of preparing a carbon material, activated carbon, a conductive additive, and a binder, wherein the pore volume of pores with a pore diameter of 17 Å or less is 30% or less of the total pore volume,

[0084] (a2) A step of preparing a conductive additive slurry by mixing the conductive additive with a dispersion aid containing a dispersion medium,

[0085] (a3) A step of preparing an electrode composition by mixing the carbon material, the activated carbon, the conductive additive slurry, and the binder,

[0086] (a4) A step of drying the electrode composition to form an electrode solid,

[0087] (a5) A step of grinding the electrode solids, and

[0088] (a6) A step of vacuum drying the electrode solids above.

[0090] The carbon material has the same characteristics as described above in the description of the carbon material included in the composite electrode for the supercapacitor mentioned above.

[0091] For example, the carbon material may have a particle size distribution of 0.01 to 5 μm at D10, 3.1 to 15 μm at D50, and 8.1 to 50 μm at D90.

[0092] The activated carbon may have a particle size distribution of 4 to 4.3 μm at D10, 5 to 5.5 μm at D50, and 6 to 6.5 μm at D90. If the particle diameter of the activated carbon is below the aforementioned range, there may be a problem with the specific surface area of ​​the activated carbon decreasing. This is because the pore structure inside the particle is destroyed, causing the surface area to be offset. Consequently, after manufacturing the electrode body, the penetration range of the binder becomes relatively wider, which may lead to an increase in resistance and a rapid decrease in capacitance. On the other hand, if the particle diameter of the activated carbon is above the aforementioned range, the voids between particles increase during the manufacturing of the electrode body, increasing the likelihood of cracking, lowering the strength of the electrode, and increasing the porosity, which may result in a decrease in the density of the electrode.

[0094] Coconut shell-based carbonized activated carbon may have a specific surface area of ​​1,500 to 3,000 m² / g and a particle size distribution of 3 to 5 µm at D10, 5 to 9 µm at D50, and 9 to 15 µm at D90. Phenol resin-based carbonized activated carbon may have a specific surface area of ​​1,500 to 3,000 m² / g and a particle size distribution of 5 to 9 µm at D10, 10 to 11 µm at D50, and 11 to 15 µm at D90. Coke pitch-based carbonized activated carbon may have a specific surface area of ​​1,500 to 3,000 m² / g and a particle size distribution of 5 to 9 µm at D10, 10 to 11 µm at D50, and 11 to 15 µm at D90.

[0096] Conductive additives can be used as additive materials in electrode compositions to compensate for the inherent low electrical conductivity and high resistance of activated carbon. As conductive additives, carbon blacks such as Ketjen black, acetylene black, or Super-P, either individually or in multiples, can be used.

[0098] As a binder, at least one of rubber-based binders such as SBR (styrene butadiene rubber), elastomer-based binders such as BM400B, or Teflon-based binders such as polytetrafluoroethylene may be used.

[0100] The step of preparing a conductive additive slurry by mixing a conductive additive with a dispersion aid containing a dispersion medium can be performed by adding the dispersion aid containing the dispersion medium to the conductive additive and performing dispersion stirring using a planetary mixer, a roll mixer, a pigment mixer, etc. The dispersion aid can be added to 40 wt% to 55 wt% of the conductive additive at a content of 45 to 60 wt%.

[0102] When using an aqueous binder as the dispersion medium, distilled water, isopropyl alcohol, ethanol, or ethyl acetate may be used alone, or distilled water may be mixed with one or two other dispersion media. In addition, when using an organic binder such as polyvinylidene fluoride (PVDF), N-methyl-pyrrolidone (NMP) may be used alone as the dispersion medium.

[0104] To improve dispersibility, the dispersion aid may further include a dispersant such as carboxymethylcellulose in addition to the dispersion medium. The dispersant may be mixed in a ratio of 0.1 to 1.0 wt% based on the total weight of the dispersion aid. For example, the step of preparing a conductive additive slurry may be performed by mixing the dispersion medium and the dispersant to prepare a dispersion aid, adding the prepared dispersion aid to the conductive additive, and then performing dispersion stirring. As a more specific example, the conductive additive slurry may be prepared by mixing carboxymethylcellulose in a dispersion medium such as distilled water, soft water, or higher alcohol at a composition of 0.1 to 1.0 wt% to prepare a dispersion aid, adding 45 to 60 wt% of the prepared dispersion aid to 40 to 55 wt% of the conductive additive, and then performing dispersion stirring.

[0106] In the step of preparing an electrode composition by mixing a carbon material, activated carbon, a conductive additive slurry, and a binder, the carbon material, activated carbon, the conductive additive slurry, and the binder may be mixed all at once, or they may be mixed sequentially. For example, the electrode composition can be prepared by first mixing the carbon material and activated carbon, then adding the conductive additive slurry to the mixture of the carbon material and activated carbon and mixing them, and finally adding the binder to the mixture of the carbon material, activated carbon, and conductive additive slurry and mixing them. Mixing can be performed by dispersion stirring using a planetary mixer, a roll mixer, a pigment mixer, etc.

[0108] At this time, the content of the mixture of carbon material and activated carbon, the conductive additive slurry, and the binder in the electrode composition may be 70 to 85 wt%: 5 to 25 wt%: 4.6 to 5.8 wt% based on the total weight of the electrode composition. Additionally, a mixture of a first binder and a second binder, which are heterogeneous binders, may be used as the binder. In this case, the content of the first binder and the second binder may be 0.1 to 0.5 wt%: 4.5 to 5.3 wt% based on the total weight of the electrode composition. The first binder may be a rubber-based SBR (styrene butadiene rubber) or an elastomer-based BM400B binder as a binder introduced first, and the second binder may be a Teflon-based polytetrafluoroethylene binder as a binder introduced later. For example, the electrode composition can be prepared in a semi-solid state by mixing 70 to 80 wt% of a mixture of carbon material and activated carbon with 15 to 25 wt% of a conductive additive slurry and performing primary dispersion stirring using a planetary mixer, a roll mixer, a pigment mixer, etc., then introducing 0.1 to 0.5 wt% of a rubber-based SBR (styrene butadiene rubber) or elastomer-based BM400B binder into a stirrer and performing secondary dispersion stirring, then introducing 4.5 to 5.3 wt% of a Teflon-based polytetrafluoroethylene binder into the stirrer and performing tertiary dispersion stirring.

[0110] The mixing ratio of carbon material and activated carbon may be a weight ratio of 1:0.1 to 1 (carbon material:activated carbon), preferably 1:0.2 to 0.8 (carbon material:activated carbon), and more preferably 1:0.3 to 0.55 (carbon material:activated carbon). If the weight ratio of activated carbon exceeds the aforementioned range, the distribution range of micropores having a diameter of less than 2 nm increases, making it difficult for the electrolyte to access the pores, and characteristics such as increased resistance, decreased electrode density, and reduced output may appear. On the other hand, if the weight ratio of activated carbon is below the aforementioned range, a negative effect of reduced capacity may occur. Therefore, it is advantageous to control the weight ratio of activated carbon within the aforementioned range.

[0112] The mixing of carbon material and activated carbon can be carried out by mixing and dispersing using a planetary mixer, a pigment mixer, etc. At this time, by rotating and dispersing at a high speed of 300 revolutions per minute (300 rpm) or more, the carbon material and activated carbon can be placed in a state where they overlap at a close distance.

[0114] The step of drying the electrode composition can be performed to remove moisture from the external and internal surfaces of the manufactured electrode composition, for example, at a temperature of 60°C to 150°C. At this time, the moisture on the surface of the electrode composition may be completely removed, but some may remain without being completely removed.

[0116] In the step of grinding the electrode solid, the electrode solid is ground into a powder or granule state. Grinding can be performed using a blade mixer or the like.

[0118] The step of vacuum drying the electrode solid can be performed to remove moisture inside the pores, and can be performed at a temperature of, for example, 150°C to 200°C.

[0120] According to the present invention, by using a mixture of a carbon material having a specific pore distribution and activated carbon in a certain weight ratio as an electrode material, the resistance of the electrode can be minimized, and the inter-particle porosity can be minimized while the electrode density can be maximized during electrode manufacturing.

[0121] The present invention controls the particle size distribution of the electrode material by adjusting the particle size distribution of the electrode material before grinding to improve the accuracy of the particle size distribution of the electrode solid after grinding, thereby enabling control of the particle size distribution of the electrode material and further maximizing the density of the electrode.

[0123] Meanwhile, in a wet coating method in which an electrode composition in a slurry state is coated onto the surface of a metal current collector such as aluminum, drying occurs simultaneously with the coating. Consequently, as the slurry dries, migration occurs in which the binder contained in the slurry rises intensively to the upper surface of the electrode due to the movement of the gasified dispersion solvent, thereby increasing the resistance of the electrode surface. Furthermore, since moisture inside the electrode must be removed while it is wound in a roll form during the manufacturing process, there is a problem in that moisture penetrating into the pores inside the winding (core) cannot be completely removed. On the other hand, in the present invention, since the electrode solid in powder or granular state is directly vacuum dried, even moisture inside the pores can be removed. Since migration does not occur, it is possible to prevent electrical performance degradation and internal pressure increase caused by the decomposition of moisture during long-term use of the supercapacitor.

[0125] In addition, according to another embodiment of the present invention, a composite film for electrodes of a supercapacitor formed by pressing a composite for electrodes of a manufactured supercapacitor can be provided.

[0127] Pressurizing a supercapacitor electrode composite in the form of vacuum-dried powder or granules can be performed using a heating roll press or the like. Pressurizing may be performed once, or it may be performed multiple times, such as two or three times. Among these, it may be preferable to pressurize the electrode composite three times. The first pressurizing may be performed by maintaining the roll surface temperature of the heating roll press at 40°C to 120°C, feeding the electrode composite in the form of powder or granules between the rolls, and pressing it to form an electrode composite film having a thickness of 170 to 200 μm. The second pressurizing may be performed by maintaining the roll surface temperature of the heating roll press at 40°C to 120°C, feeding the electrode composite film formed by the first pressurization between the rolls, and pressing it to form an electrode composite film having a thickness of 80 to 120 μm. The third pressing may be performed by maintaining the roll surface temperature of the heating roll press at room temperature of 25°C, inserting the electrode composite film formed by the second pressing between the rolls, and pressing to form an electrode composite film having a thickness of 50 to 80 μm. The third roll pressing may be performed at room temperature to minimize thickness variation of the electrode composite film.

[0129] In addition, according to another embodiment of the present invention, an electrode of a supercapacitor comprising a composite film for the electrode of a supercapacitor manufactured according to another embodiment of the present invention may be provided.

[0131] An electrode of a supercapacitor according to another embodiment of the present invention can be manufactured through a manufacturing method comprising the following steps.

[0132] (b1) Step of manufacturing a conductive layer paste,

[0133] (b2) A step of manufacturing an electrode current collector having a conductive layer formed thereon by coating the above conductive layer paste onto a metal foil and drying it,

[0134] (b3) a step of vacuum drying the electrode current collector having the conductive layer formed thereon, and

[0135] (b4) A step of placing an electrode composite film on an electrode current collector having the conductive layer formed thereon so as to face the conductive layer and applying pressure.

[0137] The conductive layer paste is intended for bonding an electrode composite film to an electrode current collector and comprises a carbon material with excellent electrical conductivity and a conductive additive slurry, and may further comprise a binder. The conductive paste can be manufactured, for example, by mixing the carbon material and the conductive additive slurry and performing primary dispersion stirring using a planetary mixer, a roll mixer, a pigment mixer, etc., and then adding a binder to the primary slurry thus prepared and performing secondary dispersion stirring. At this time, the carbon material, the conductive additive slurry, and the binder may be mixed in a ratio of 10 to 20 wt%: 70 to 90 wt%: 5 to 10 wt%. The carbon material and the conductive additive slurry may be the same as the carbon material and the conductive additive slurry included in the electrode composite of the supercapacitor described above, and a detailed description thereof will be omitted. The binder may also be the same as the binder included in the electrode composite of the supercapacitor described above, for example, a rubber-based SBR (styrene butadiene rubber) or an elastomer-based BM400B may be used. The viscosity of the manufactured conductive layer paste may be 10,000 to 100,000 cP, and the sheet resistance may be 0.5 Ω / cm³ to 5.0 Ω / cm³.

[0139] In the step of manufacturing an electrode current collector having a conductive layer formed by coating a conductive layer paste onto a metal foil and drying it, the coating may be performed by known methods such as a doctor blade, comma roll, gravure, or spray coating. The conductive layer paste may be coated on one or both sides of the metal foil. When coating, the coating thickness may be adjusted so that the thickness of the conductive layer formed after drying is 1 to 10 μm, for example, it may be coated with a thickness of 10 to 50 μm. The metal foil may be aluminum foil or etched aluminum foil, etc., and the thickness of the metal foil may be 5 to 50 μm, but is not limited thereto. Drying may be performed at a temperature of, for example, 40°C to 120°C.

[0141] The step of vacuum drying the electrode current collector having the conductive layer formed thereon can be performed to remove moisture, for example, at a temperature of 150°C to 200°C.

[0143] In the step of forming an electrode by placing an electrode composite film facing the conductive layer on an electrode current collector having a conductive layer formed thereon and applying pressure, the pressure may be performed using a heating roll press, etc. For example, the above step may be performed by placing an electrode composite film on one or both sides of an aluminum current collector having a conductive layer formed on one or both sides, and by applying pressure molding once while maintaining the roll surface temperature of the heating roll press at 40°C to 120°C. The thickness of the electrode after pressure may be 85% or more of the total thickness obtained by adding the thickness of the electrode composite film before pressure and the thickness of the electrode current collector having the conductive layer formed thereon. This is because if the thickness of the electrode after pressure is less than the above range, it is difficult for the electrolyte to penetrate into the pores, which may result in a loss of electrical performance of the supercapacitor, and the expansion rate of the electrode increases during charging and discharging of the supercapacitor, thereby increasing the possibility of cracking in the separator.

[0145] The electrode of a supercapacitor manufactured by the method for manufacturing a supercapacitor electrode according to the present invention may have a high electrode density of 0.85 to 1.65 g / cm³ and a low electrode surface resistance of 1 to 200 Ω / sqm. Accordingly, the supercapacitor electrode according to the present invention may be formed with a thinner thickness compared to other electrodes of the same capacitance, and may exhibit a high output density due to high capacitance and low resistance characteristics resulting from the high electrode density compared to other electrodes having the same thickness or volume.

[0147] In addition, according to another embodiment of the present invention, a supercapacitor comprising an electrode of a supercapacitor manufactured according to another embodiment of the present invention may be provided.

[0149] The present invention will be described in more detail below through examples and comparative examples.

[0151] Meanwhile, the following manufacturing examples and embodiments are merely for the purpose of explaining the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace the following manufacturing examples and embodiments may exist at the time of filing this application.

[0153] Manufacturing Example: Manufacturing of carbon material

[0154] According to the steps (s1) to (s3) described above, a carbon material was produced using biochar formed by carbonizing oak wood with biomass. At this time, in step (s1), all of the carbonization steps 1 to 6 described above were performed, in step (s2), the biochar was ground with a ball mill, and in step (s3), all of the first to third impurity removal steps described above were performed.

[0155] In the carbon material prepared according to the example, the pore volume of pores with a pore diameter of 17 Å or less was measured to be 23.39% of the total pore volume.

[0156] In addition, the specific surface area of ​​the carbon material prepared according to the preparation example was 62.55 m² / g, and the particle size distribution was 3.4 µm at D10, 5.9 µm at D50, and 9.1 µm at D90.

[0157] In addition, the tap density of the carbon material manufactured according to the manufacturing example was 1.6 g / cm³.

[0158] Referring to Fig. 4, the D peak / G peak intensity ratio by Raman analysis of the carbon material prepared according to the preparation example was measured to be 0.49 and the 2D peak / G peak intensity ratio was measured to be 1.045, and it appears to have a single or a few layered structure. On the other hand, referring to Fig. 5, the commercially available graphene generally has a D peak / G peak intensity ratio by Raman analysis of 1.16 and a 2D peak / G peak intensity ratio was measured to be 0.32, and it appears to have strong crystallinity and a single or more (a few) layered structure.

[0159] Referring to Fig. 6, the electrical conductivity of the carbon material prepared according to the preparation example was 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, was 5.384 S / cm at 1,999 kgf, which is less than 10% of the electrical conductivity of the carbon material prepared according to the preparation example.

[0160] 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 prepared according to the example of the present invention was measured to be 98.72 wt% and the oxygen (O) content was 1.09 wt%.

[0162] element Weight ratio (wt%) wt% Sigma Atomic % C 98.72 0.06 99.1 N 0 0 0 O 1.09 0.06 0.82 Na 0 0 0 Si 0.18 0.02 0.08 S 0 0 0 Total: 100 　 100

[0163] Table 1: TEM analysis results of the carbon material according to the manufacturing example of the present invention

[0164] Example 1: Preparation of a composite for electrodes of a supercapacitor

[0165] Example 1-1

[0166] A dispersion aid was prepared with a composition of distilled water and 0.2 wt% carboxymethylcellulose (the amount of dispersion aid is such that the ratio of carboxymethylcellulose is 0.2 wt% based on the total mass of the powdered conductive additive, powdered carbon material, activated carbon, and binder), and a conductive additive slurry was prepared by adding the prepared dispersion aid to 10 wt% of the powdered conductive additive Super-P and then performing dispersion stirring with a planetary mixer.

[0167] A mixed powder of powdered carbon material having a particle size distribution of 3.4 μm at D10, 5.9 μm at D50, and 9.1 μm at D90, with a specific surface area of ​​1,500 m² / g and a particle size distribution of 3 μm at D10, 7 μm at D50, and 15 μm at D90, was added to the prepared conductive additive slurry, and the mixture was dispersed and stirred using a planetary mixer to prepare a solid slurry. At this time, the powdered carbon material and the activated carbon were added at a weight ratio of 8:2 (carbon material:activated carbon) at 85 wt% based on the total weight of the electrode composition to prepare the solid slurry.

[0168] 95.2 wt% of the manufactured solid slurry (0.2 wt% dispersion aid, 10 wt% powdered conductive additive, 85 wt% powdered carbon material and activated carbon) and 0.3 wt% of SBR binder were fed into a stirrer and subjected to secondary dispersion stirring, then mixed with 4.5 wt% of polytetrafluoroethylene binder and subjected to tertiary dispersion stirring to produce a semi-solid electrode composition.

[0169] The prepared electrode composition was dried at a temperature of 100°C, and the electrode solid from which moisture had been removed was ground using a blade mixer so that the electrode solid became a granule. Next, the electrode solid in the granule state was vacuum dried at a temperature of 150°C to prepare a composite for the electrode of a supercapacitor.

[0171] Examples 1-2

[0172] A composite for the electrode of a supercapacitor was prepared in the same manner as in Example 1-1, except that the weight ratio of the carbon material and the activated carbon was mixed in a ratio of 7:3.

[0174] Examples 1-3

[0175] A composite for the electrode of a supercapacitor was prepared in the same manner as in Example 1-1, except that the weight ratio of the carbon material and the activated carbon was mixed in a 6:4 ratio.

[0177] Examples 1-4

[0178] A composite for the electrode of a supercapacitor was prepared in the same manner as in Example 1-1, except that the weight ratio of the carbon material and the activated carbon was mixed in a 5:5 ratio.

[0180] Comparative Example 1-1

[0181] A dispersion aid was prepared with a composition of distilled water and 0.2 wt% carboxymethylcellulose, and a conductive additive slurry was prepared by adding the prepared dispersion aid (where the amount of dispersion aid is such that the ratio of carboxymethylcellulose is 0.2 wt% based on the total mass of the powdered conductive additive, powdered carbon material, activated carbon, and binder) to 5 wt% of powdered conductive additive Super-P and then performing dispersion stirring with a planetary mixer.

[0182] 90 wt% of coconut shell-based carbonized activated carbon (YP-50) powder was added to the prepared conductive additive slurry, the pore volume of pores with a pore diameter of 17 Å or less was 86% of the total pore volume, the specific surface area was 1,500 m² / g, and the particle size distribution was 3 μm at D10, 7 μm at D50, and 15 μm at D90, and the mixture was dispersed and stirred with a planetary mixer to prepare a solid slurry.

[0183] A semi-solid electrode composition was prepared by introducing the manufactured solid slurry and 0.3 wt% SBR binder into a stirrer and performing secondary dispersion stirring, then mixing with 4.5 wt% polytetrafluoroethylene binder and performing tertiary dispersion stirring.

[0184] The prepared electrode composition was dried at a temperature of 100°C, and the electrode solid from which moisture had been removed was ground using a blade mixer until the electrode solid became a powder. Next, the electrode solid in powder form was vacuum dried at a temperature of 150°C to produce activated carbon electrode powder.

[0186] Example 2: Preparation of a composite film for electrodes of a supercapacitor

[0187] Example 2-1

[0188] The surface temperature of the rolls of the heating roll press was maintained at 80°C, and the composite film for the electrode of the supercapacitor according to Example 1-1 was introduced between the rolls and subjected to a first pressure molding to a thickness of 180 to 190 μm. Next, the surface temperature of the rolls of the heating roll press was maintained at 40°C, and the composite film for the electrode of the supercapacitor subjected to the first pressure molding was subjected to a second pressure molding to a thickness of 100 to 110 μm. Subsequently, the surface temperature of the rolls of the heating roll press was maintained at room temperature of 25°C, and the composite film for the electrode of the supercapacitor subjected to the second pressure molding was subjected to a third pressure molding to a thickness of 60 μm to manufacture the composite film for the electrode of the supercapacitor.

[0190] Example 2-2

[0191] In addition to using the composite for the electrode of the supercapacitor according to Example 1-2, a composite film for the electrode of the supercapacitor was prepared in the same manner as in Example 2-1.

[0193] Examples 2-3

[0194] In addition to using the composite for the electrode of the supercapacitor according to Examples 1-3, a composite film for the electrode of the supercapacitor was prepared in the same manner as in Example 2-1.

[0196] Examples 2-4

[0197] In addition to using the composite for the electrode of the supercapacitor according to Examples 1-4, a composite film for the electrode of the supercapacitor was prepared in the same manner as in Example 2-1.

[0199] Comparative Example 2-1

[0200] The surface temperature of the rolls of a heating roll press was maintained at 80°C, and the activated carbon electrode powder according to Comparative Example 1-1 was introduced between the rolls, and a first pressure molding was performed to a thickness of 200 to 210 μm. Next, the surface temperature of the rolls of the heating roll press was maintained at 60°C, and the first pressure-molded activated carbon film was second pressure-molded to a thickness of 100 to 110 μm. After that, the surface temperature of the rolls of the heating roll press was maintained at room temperature of 25°C, and the second pressure-molded activated carbon film was third pressure-molded to a thickness of 80 to 85 μm to produce an activated carbon film.

[0202] Example 3: Preparation of electrodes for a supercapacitor

[0203] Example 3-1

[0204] 13 wt% of carbon material powder prepared according to the preparation example was mixed with 80 wt% of the conductive additive slurry prepared in Example 1-1, and after primary dispersion stirring using a planetary mixer, the prepared primary slurry and 7 wt% of SBR binder were introduced into a stirrer and secondary dispersion stirring was performed to prepare a conductive layer paste having a viscosity of 60,000 cP. The prepared conductive layer paste was coated to a thickness of 15 μm on one side of an 18 μm aluminum foil using a doctor blade, dried at a temperature of 100°C to form a conductive layer with a thickness of 4 μm, and then vacuum dried at a temperature of 150°C to remove moisture. A composite film according to Example 2-1 was placed on an aluminum current collector having the conductive layer formed thereon, and pressure molding was performed once while maintaining the roll surface temperature of a heating roll press at 80°C.

[0205] The total thickness of the electrodes of the supercapacitor completed after roll pressing was 78 μm, and the electrode density was 1.17 g / cm³. The specific capacity was calculated as 56 μm, excluding the thickness of the electrode current collector with the conductive layer formed thereon, which is 22 μm, from the total thickness of the supercapacitor electrodes, which is 78 μm.

[0207] Example 3-2

[0208] Except for using the composite film for the electrode of the supercapacitor according to Example 2-2, the electrode of the supercapacitor was manufactured in the same manner as in Example 3-1.

[0209] The total thickness of the electrode was 80㎛ and the electrode density was 1.10 g / cm³. The specific capacity was calculated as 60㎛, excluding the thickness of the electrode current collector with the conductive layer formed thereon, from the total thickness of the supercapacitor's electrode, 80㎛.

[0211] Example 3-3

[0212] Except for using the composite film for the electrode of the supercapacitor according to Example 2-3, the electrode of the supercapacitor was manufactured in the same manner as in Example 3-1.

[0213] The total thickness of the electrode was 80㎛ and the electrode density was 1.04 g / cm³. The specific capacity was calculated as 60㎛, excluding the thickness of the electrode current collector with the conductive layer formed thereon, from the total thickness of the supercapacitor's electrode, 80㎛.

[0215] Examples 3-4

[0216] Except for using the composite film for the electrode of the supercapacitor according to Example 2-4, the electrode of the supercapacitor was manufactured in the same manner as in Example 3-1.

[0217] The total thickness of the electrode was 92 μm, and the electrode density was 0.99 g / cm³. The specific capacity was calculated as 70 μm, excluding the thickness of the electrode current collector with the conductive layer formed thereon, from the total thickness of the supercapacitor electrode, which was 92 μm.

[0219] Comparative Example 3-1

[0220] 80 wt% of carbon material powder prepared according to the preparation example was mixed with 13 wt% of the conductive additive slurry prepared in Comparative Example 1-1, and after primary dispersion stirring using a planetary mixer, the prepared primary slurry and 7 wt% of SBR binder were introduced into a stirrer and secondary dispersion stirring was performed to prepare a conductive layer paste having a viscosity of 60,000 cP. The prepared conductive layer paste was coated to a thickness of 15 μm on one side of an 18 μm aluminum foil using a doctor blade, dried at a temperature of 100°C to form a conductive layer with a thickness of 4 μm, and then vacuum dried at a temperature of 150°C to remove moisture. An activated carbon film according to Comparative Example 2-1 was placed on the aluminum current collector on which the conductive layer was formed, and pressure molding was performed once while maintaining the roll surface temperature of a heating roll press at 80°C.

[0221] That is, the electrode of the supercapacitor was prepared in the same manner as in Example 3-1, except that the conductive additive slurry prepared in Comparative Example 1-1 and the activated carbon film of the supercapacitor according to Comparative Example 2-1 were used.

[0222] The total thickness of the activated carbon electrode body completed after roll pressing was 125 μm, and the electrode density was 0.64 g / cm³. The specific capacity was calculated as 103 μm, excluding the thickness of the electrode current collector with the conductive layer formed thereon (22 μm) from the total thickness of the activated carbon electrode body (125 μm).

[0224] Experimental Example: Fabrication and Evaluation of Supercapacitors

[0225] Electrodes according to Examples 3-1 to 3-4 and Comparative Example 3-1, respectively, were punched to produce electrodes with a diameter of 16 mm in the form of coins. Next, an insulating gasket made of polypropylene (PP) was placed between the metal cases of the anode and cathode, each made of SUS metal, to prevent short circuits caused by contact between metal cases of different polarities and leakage of the liquid electrolyte component present inside the unit cell. Then, a certain amount of an organic electrolyte with a concentration of 0.1 N, containing acetonitrile as a solvent and tetraethylammonium tetrafluoroborate (TEABF4) as a solute, was impregnated onto the electrode surfaces located inside the metal cases of the anode and cathode, respectively, and a separator made of porous nonwoven fabric was placed between the electrodes to prevent short circuits caused by contact between electrodes of different polarities. Subsequently, to achieve effective airtightness, a unit cell was produced by clamping the outermost rim of the lower metal case, which is the part to be directly clamped, the outermost rim of the gasket in contact with the outermost rim of the lower metal case, and the outermost rim of the upper metal case in contact with the inner rim of the outermost rim of the gasket, by pressing from the outermost rim of the lower metal case to the center of the cell using a clamping die.

[0226] For each supercapacitor including electrodes prepared according to the examples and comparative examples, a test was conducted with a charging voltage of 2.7 V, a charging current equal to the discharge current, a charging time of 1 hour after the charging voltage reached 2.7 V, and a discharge current of 1 mA. At this time, electrode surface resistance, electrode resistivity, leakage current (LC), and AC resistance (ESR) AC ), DC resistance (ESR DC ), capacitance (CAP) and specific capacity were measured, and the results are shown in Table 2 below.

[0227] In the table below, Experimental Examples 1 to 4 and Comparative Experimental Example 1 represent the measurement results of supercapacitors including electrodes prepared according to Examples 3-1 to 3-4 and Comparative Example 3-1, respectively.

[0229] item Electrode surface resistance Electrode resistivity LC ESR AC ESR DC CAP Cost unit (Ω / sqm) (S / ㎝) (㎃) (Ω) (Ω) (F) (F / ㎤) Experimental Example 1 50.2 1.32 0.11 1.16 5.9 0.25 11.10 Experimental Example 2 68.5 0.93 0.22 1.20 6.3 0.34 14.09 Experimental Example 3 107.8 0.61 0.35 1.30 6.8 0.42 17.41 Experimental Example 4 153.1 0.38 0.38 1.40 6.9 0.42 14.92 Comparative Experiment Example 1 1,374.0 0.20 0,39 3.46 12.26 0.43 10.38

[0230] The outputs of Experimental Examples 1 to 4 and Comparative Experimental Example 1, respectively, are as shown in Table 3 below.

[0232] item output of power Electrode weight Output density unit (W) (g) (kW / kg) Experimental Example 1 0.3089 0.022 11.73 Experimental Example 2 0.2893 0.024 10.90 Experimental Example 3 0.2680 0.024 10.68 Experimental Example 4 0.2641 0.028 9.48 Comparative Experiment Example 1 0.1487 0.041 5.61

[0233] In this case, the output can be calculated using the following function.

[0234] P = V 2 / (4*ESR DC )

[0235] Here, P is Power, V is Voltage, and ESR DC ρ is the DC resistance, and the unit of output is W. From this, it can be seen that under the same voltage conditions, the smaller the DC resistance, the better the output.

[0237] In the case of an embodiment in which a specific carbon material and activated carbon are mixed and used as electrode materials for a supercapacitor, compared to a comparative example in which activated carbon is used alone, electrodes with low DC resistance and high density are provided, thereby allowing the capacitance and output of the supercapacitor to be designed complementarily; that is, it is possible to improve the output of the supercapacitor while also securing a certain level of capacitance, and a technology is provided to control the final performance, and economic benefits can also be provided by manufacturing the carbon material using biochar produced by carbonizing biomass.

[0239] Although an exemplary embodiment of the present invention has been described above, the embodiments of the present invention are not intended to be limited to the aforementioned embodiments. Those skilled in the art may appropriately modify and implement an embodiment of the present invention, such as omitting, changing, or substituting all or part of the components of the present invention, or adding other components, by referring to this specification and the accompanying drawings, without departing from the technical spirit of the present invention.

[0241] The terms and expressions in this specification should be interpreted broadly and not restrictively. In this specification, the expression “comprising” does not exclude the presence or addition of one or more other components in addition to the mentioned components. Also, in this specification, the expression “to” means including upper and lower limit values. For example, 1 to 10 means including the upper limit value of 10 and the lower limit value of 1, and may also be expressed as 1 or more and 10 or less.

[0243] Each of the embodiments described by way of example in this specification may be combined with one another, and unless contradictory, the contents described in a particular embodiment may be equally applied to other embodiments even if they are not described in other embodiments.

Claims

Claim 1 A composite for an electrode of a supercapacitor comprising: a carbon material having a pore volume of pores with a pore diameter of 17 Å or less that is 30% or less of the total pore volume; and activated carbon; wherein the weight ratio of the carbon material and the activated carbon is 1:0.1 to 1, and the tap density of the carbon material is 0.4 g / cm³ or more and 2.0 g / cm³ or less. Claim 2 delete Claim 3 A composite for electrodes of a supercapacitor according to claim 1, wherein the carbon material has a carbon (C) content of 98 wt% or more and an oxygen (O) content of less than 2 wt%. Claim 4 A composite for an electrode of a supercapacitor according to claim 1, wherein the D peak / G peak intensity ratio by Raman analysis of the carbon material is 0.1 to 0.9 and the 2D peak / G peak intensity ratio is 0.5 to 1.

5. Claim 5 A composite for electrodes of a supercapacitor according to claim 1, wherein the electrical conductivity of the carbon material is 61 S / cm to 76 S / cm at 2,000 kgf. Claim 6 In claim 1, the carbon material is D 10 At 1 to 5㎛, D 50 At 10 to 15㎛, D 90 A composite for electrodes of a supercapacitor having a particle size distribution of 8.1 to 50 μm. Claim 7 In claim 1, the specific surface area of ​​the carbon material is 1 m² 2 / g to 200m 2 A composite for electrodes of a supercapacitor that is / g. Claim 8 A composite for electrodes of a supercapacitor, further comprising a conductive additive in claim 1. Claim 9 A composite for electrodes of a supercapacitor, further comprising a binder in claim 1. Claim 10 An electrode of a supercapacitor comprising a composite for the electrode of a supercapacitor according to claim 1. Claim 11 In claim 10, the electrode of the supercapacitor has a density of 0.85 to 1.65 g / cm³. Claim 12 A supercapacitor comprising electrodes of a supercapacitor according to paragraph 10.

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