KR102337540B1 - Electric double layer capacitor and method of producing the same - Google Patents

Abstract

The embodiment relates to an electric double layer capacitor and a method of manufacturing the same, and more particularly, a first electrode, a second electrode disposed to be spaced apart from the first electrode, and a separator disposed between the first electrode and the second electrode and an electrolyte impregnating the first electrode, the second electrode, and the separator, wherein the first electrode and the second electrode each include a current collector and an electrode mixture layer disposed on at least one surface of the current collector, The electrolyte includes a first ion and a first solvent, the first ion includes a first cation and a first anion, the electrode mixture layer includes activated carbon and a salt, and the activated carbon includes a plurality of pores, and the plurality of The pores of the pore include a pore inlet and an inner region in communication with the pore inlet, wherein the pore inlet includes a pore inlet that is smaller than the size of the first cation or the size of the first anion, and the inner region includes the first Including the inner region larger than the size of the cation or the first anion, and the first solvent flows into the inner region through the pore inlet to dissociate the salt, thereby improving the availability of pores present in the electrode Accordingly, the present invention relates to an electric double layer capacitor capable of realizing high energy density by improving capacitance and a method for manufacturing the same.

Description

Electric double layer capacitor and manufacturing method thereof

The embodiment relates to an electric double-layer capacitor and a method for manufacturing the same, and more particularly, to an electric double-layer capacitor having improved capacitance and energy output characteristics and a method for manufacturing the same.

Recently, interest in energy storage technology is increasing.

Efforts for research and development of electrochemical devices are becoming more and more concrete as the field of application is expanded to the energy of mobile phones, camcorders, notebook PCs, and even electric vehicles.

An electrochemical device enables conversion between electrical energy and chemical energy, and specific examples include an electric double layer capacitor (EDLC), a lithium ion secondary battery, a hybrid capacitor, and the like.

Electrochemical devices are attracting attention in terms of being able to charge and discharge and have high energy density, and high capacitance and energy density are required according to the expansion of application fields.

In an electric double layer capacitor, electric double layers having different signs are generated at the interface of an electrolyte solution impregnated with an electrode and a conductor to accumulate electric charges.

However, electric double-layer capacitors have small deterioration even after repeated charging and discharging, and have excellent charging speed and high output density compared to other energy storage devices such as secondary batteries and lead acid batteries. have.

As the capacitance or the operating voltage increases, the energy density of the electric double layer capacitor is improved. In order to overcome the disadvantages of the electric double layer capacitor, research on a method of increasing the capacitance or the operating voltage is being actively conducted.

The performance of the electric double layer capacitor can be mainly determined by the electrode active material and the electrolyte. Accordingly, there is a need for an alternative for increasing the energy density of the electric double layer capacitor by a method such as increasing the capacitance without occurrence of defects in the electrode.

An object of the embodiment is to provide an electric double layer capacitor capable of realizing a high energy density by improving the capacitance by improving the availability of pores present in the electrode.

The electric double layer capacitor of the embodiment includes a first electrode, a second electrode spaced apart from the first electrode, a separator disposed between the first electrode and the second electrode, and the first electrode, the second electrode, and the separator and an electrolyte to be impregnated, wherein the first electrode and the second electrode each include a current collector and an electrode mixture layer disposed on at least one surface of the current collector, and the electrolyte includes a first ion and a first solvent, The first ion includes a first cation and a first anion, and the electrode mixture layer includes activated carbon and a salt, the activated carbon includes a plurality of pores, and the plurality of pores have a pore inlet and an interior communicating with the pore inlet. and wherein the pore inlet includes a pore inlet that is smaller than the size of the first cation or the size of the first anion, and the inner region is larger than the size of the first cation or the size of the first anion. and an inner region, and the first solvent may flow into the inner region through the pore inlet to dissociate the salt.

According to an embodiment, the salt may be dissociated by the first solvent introduced into the pore inlet to exist as a second ion.

According to an embodiment, the plurality of pores may include pores having a salt not dissociated by the first solvent.

According to an embodiment, the second ion may include both a second cation and a second anion.

According to one embodiment, the second cation may include two or more kinds of cations having different sizes, or the second anion may include two or more kinds of anions having different sizes.

According to an embodiment, the first ion may include the same ion as the second ion.

According to one embodiment, the second ion is at least one selected from the group consisting ^{of TMA +} , TEA ⁺ , TBA ⁺ , TMEA ⁺ , TEMA ⁺ , SBP ⁺ , BF ₄ ^- , TFSI ^- and CF ₃ SO ₃ ^- can

According to an embodiment, the number of pores having a diameter (D) of 0.5 nm or more and 1.1 nm or less with respect to all pores present in the electrode mixture layer may be 35% by volume to 85% by volume or less.

The manufacturing method of the electric double layer capacitor of the embodiment comprises the steps of heat-treating activated carbon at a temperature of 600 or more and 900 or less, mixing the heat-treated activated carbon and an alkali-containing activator in a weight ratio of 1:1.5 or more and 1:4 or more to obtain 700 or more and 900 or less. Activating at a temperature, neutralizing the activated material, mixing the neutralized material, a binder, a conductive material, and an electrode material including a salt and then pressurizing the pressurized material on at least one surface of the current collector and forming an electrode mixture layer by coating the activated carbon, wherein the activated carbon includes a crystalline structure and an amorphous structure, and the amorphous structure includes a plurality of pores having a diameter (D) of 2 nm or less, and the electrode material total 100 weight %, the activated carbon is included in 50 wt% or more and 95 wt% or less, the binder is included in 1 wt% or more and 30 wt% or less, the conductive material is included in 1 wt% or more and 30 wt% or less, and the salt is It may contain 1 wt% or more and 10 wt% or less.

The electric double layer capacitor of the embodiment can maximize the pores used as ions adsorption and desorption space.

That is, by including the electrode formed of the electrode material according to the embodiment, the salt is present in the inner region of the pores, and even if the ions contained in the electrolyte do not flow into the pores, the Salts present in the inner region may be dissociated.

Accordingly, ions present in the internal region of the pores can be adsorbed and desorbed in the internal region during charging and discharging, so even without increasing the physical specific surface area of the carbon source, it significantly improves the usability of the pores present in the electrode, thereby increasing the electrostatic capacity. High energy density realization of electric double layer capacitors may be possible.

In addition, since the electrolyte flows into the inner region of the pores, wettability is improved and the cell internal resistance is reduced, thereby improving energy output characteristics.

1 is a diagram schematically illustrating an electric double layer capacitor according to an embodiment.
2 is a manufacturing process diagram of an electrode material according to an embodiment.
3 is a diagram schematically illustrating changes in activated carbon according to heat treatment and activation treatment.
4 is an enlarged view of part A of FIG. 3 .
5 is a diagram schematically illustrating ions present in activated carbon according to an embodiment.

In the description of embodiments, each layer, film, electrode, plate or substrate, etc. is described as being formed “on” or “under” each layer, film, electrode, plate or substrate, etc. In some instances, “on” and “under” include both “directly” or “indirectly” formed through another element.

In addition, the criteria for the upper, side, or lower of each component will be described with reference to the drawings.

1 is a diagram schematically showing an electric double layer capacitor according to an embodiment, FIG. 2 is a manufacturing process diagram of an electrode material according to an embodiment, and FIG. 3 is a diagram schematically showing changes in activated carbon according to heat treatment and activation treatment 4 is an enlarged view of part A of FIG. 3 , and FIG. 5 is a diagram schematically illustrating ions present in activated carbon according to an embodiment. Hereinafter, the embodiment will be described in detail with reference to FIGS. 1 to 5 .

The electric double layer capacitor 10 of the embodiment includes a first electrode 2 , a second electrode 4 spaced apart from the first electrode 2 , the first electrode 2 and the second electrode 4 . It may include a separation membrane 3 disposed therebetween. Meanwhile, the terminals of the first electrode 2 and the second electrode 4 may be combined.

According to an embodiment, the first electrode 2 may be an anode, and the second electrode 4 may be a cathode. Hereinafter, an electric double layer capacitor of the embodiment will be described on the premise of this.

The separator 3 may be disposed between the first electrode 2 and the second electrode 4 . Specifically, the separator 3 may be disposed in contact with the first electrode 2 and the second electrode 4 . One surface and the other surface of the separator 3 may be disposed in direct contact with the first electrode 2 and the second electrode 4 .

If necessary, the electric double layer capacitor 10 may include two or more separators.

According to an embodiment, when the electric double layer capacitor 10 includes a plurality of separators, the separator 1 other than the separator 3 disposed between the first electrode 2 and the second electrode 4 is It may be disposed on the first electrode 2 .

Meanwhile, the first electrode 2 and the second electrode 4 may include a current collector 8 and an electrode mixture layer 9 disposed on at least one surface of the current collector 8 , respectively.

That is, the first electrode 2 includes a first current collector and a first electrode mixture layer disposed on at least one surface of the first current collector, and the second electrode 4 includes a second current collector and the first current collector. It may include a second electrode mixture layer disposed on at least one surface of the second current collector. More specifically, the current collector 8 and the electrode mixture layer 9 coated with an electrode material to be described later on at least one surface of the current collector 8 is formed by the first electrode 2 and the second electrode 4 . can be included in

The electrolyte may impregnate the first electrode 2 , the second electrode 4 , and the separator 3 .

The electrolyte may include a first ion 13 and a first solvent 16 . That is, the first ions 13 may be ions included in the electrolyte.

In addition, the first ion 13 may include a first cation and a first anion.

More specifically, specific examples of the first cation included in the electrolyte may be TMA ⁺ , TEA ⁺ , TBA ⁺ , TMEA ⁺ , TEMA ⁺ , SBP ^{+ and the} like. Each of these may be used alone or in combination of two or more.

The sizes of the first cations are shown in Table 1 below.

Kinds size [nm] TBA 0.830 TMA 0.566 TMEA 0.596 TEMA 0.654 TEA 0.686 SBP 0.593

In addition, specific examples of the first anion included in the electrolyte solution include BF ₄ ^- , PF ₆ ^- , CF ₃ SO ₃ ^- , FSI ^{- and the} like. Each of these may be used alone or in combination of two or more.

In addition, the size of the first anion is shown in Table 2 below.

Kinds size [nm] BF ₄ ^- 0.458 TFSI ^- 0.650 CF ₃ SO ₃ ^- 0.54

Considering the size of the first cation and the first anion and the size of the pore inlet 15 , it may be preferable to use a ^{cation including TEA +} and an anion including BF ₄ ^{− .}

In addition, the first solvent 16 is more specifically ACN (Acetonitrile, 41.05 g / mol), PC (Propylene Carbonate, 102.09 g / mol), SL (Sulfolane, 120.17 g / mol), ADN (Adiponitrile, 108.14) g/mol) EC (Ethylene Carbonate, 88.06 g/mol), DMC (Dimethyl Carbornate, 90.08 g/mol), EMC (Ethyl Methyl Carbonate, 104.11 g/mol) DMS (Dimethyl Sulfone, 94.13 g/mol), EMS ( Ethyl Methane Sulfonate, 124.16 g/mol), GBL (GAMMA BUTYROLACTONE), DMK (DIMETHYL KETONE), and the like.

The sizes of ACN and PC in the first solvent 16 are shown in Table 3 below.

Kinds size [nm] ACN 0.427 PC 0.610

Meanwhile, although not shown in Table 3 below, the size of the first solvent 16 may be predicted in consideration of the molar mass of the molecule and the structure of the molecule.

The concentration of the electrolyte may be different for each type of the first solvent 16 and the first ions 13 included in the electrolyte.

The current collector 8 included in the first electrode 2 and the second electrode 4 may include a conductive material. Specific examples of the conductive material may be metal or the like. More specifically, the metal may be copper, aluminum, or the like, but the present invention is not necessarily limited to the embodiments. The current collector 8 may have a thin film shape.

Meanwhile, the electrode mixture layer 9 included in the first electrode 2 and the second electrode 4 may be formed of an electrode material, and the electrode material may include activated carbon 100 and a salt. .

The electrode mixture layer 9 may include activated carbon 100 and a salt.

Activated carbon 100 according to the embodiment may include a crystalline structure 21 .

The crystalline structure 21 may be formed in the activated carbon by heat-treating the activated carbon under specific conditions. More specifically, the crystalline structure 21 may be formed as partial crystallization proceeds in the activated carbon 100 during heat treatment of the activated carbon from which impurities are separated at a temperature of 600 to 900.

If the temperature of the heat treatment is less than 600 ° C., the crystalline structure 21 may not be formed in the activated carbon 100 . In addition, when the heat treatment temperature exceeds 900 ° C., only the crystalline structure 21 may exist without the amorphous structure 11 in the activated carbon 100 . In this case, since the specific surface area is reduced, there is a problem in that high capacitance cannot be realized. That is, the activated carbon 100 is heat-treated at a temperature of 600 ℃ to 900 ℃ to form a crystalline structure 21 in the activated carbon 100, the activated carbon 100 has a crystalline structure 21 and an amorphous structure 11 all can be included.

In an embodiment, the heat treatment temperature may be 650 °C to 850 °C.

The ratio of the crystalline 21 to the unit weight (g) of the activated carbon 100 may be controlled by the heat treatment temperature of the activated carbon 100 .

The ratio of the crystalline structure 21 to the unit weight (g) of the activated carbon 100 varies according to the heat treatment temperature of the activated carbon 100, and the ratio of the crystalline structure 21 is the ratio of the activated carbon 100 Affecting the surface area can change the capacitance value.

More specifically, the lower the heat treatment temperature of the activated carbon 100, the higher the ratio of the amorphous structure 11, the specific surface area of the activated carbon 100 increases, and the higher the heat treatment temperature of the activated carbon 100, the higher the crystalline structure 21 ) may be increased to decrease the specific surface area of the activated carbon 100 .

The time for which the heat treatment process is performed may vary depending on the size of the reaction tank.

The heat treatment may be performed in an inert gas atmosphere. Specific examples of the inert gas may be helium, argon, nitrogen, or the like. The inert gas may be used including at least one of the above-described examples, but the embodiment is not necessarily limited thereto.

According to an embodiment, the crystalline structure 21 may serve as a movement path for the first ions 13 so that the first ions 13 can easily flow. Accordingly, when the electrical resistance is lowered, the activated carbon 100 and the electrical conductivity and/or the electrostatic capacity of the electric double-layer capacitor formed including the activated carbon 100 may be improved.

Whether the activated carbon 100 includes the crystalline structure 21 may be confirmed by X-ray diffraction (XRD).

When a crystal is irradiated with X-rays, diffraction may occur in a part of the crystal, and the diffraction angle and intensity are unique to each material. . That is, according to the X-ray diffraction analysis method, information on the structure of the crystalline structure material can be known. More specifically, in the X-ray diffraction pattern, a peak means the presence of a crystalline structure, and the peak intensity is related to the proportion of the crystalline structure. In addition, the ratio of the amorphous structure can also be known from the X-ray diffraction pattern, and the width of the half-width is related to the ratio of the amorphous structure.

Therefore, when a peak (Intensity) appears at a specific position in the X-ray diffraction pattern, it is a case that a crystalline structure is included, and the higher the peak appears, the more the crystalline structure is included. In addition, the larger the half width in the X-ray diffraction pattern, the more the amorphous structure is included in the activated carbon.

The activated carbon 100 may include an amorphous structure 11 . Even when a specific process is not performed on the activated carbon, the amorphous structure 11 may be included in the activated carbon 100 .

That is, the heat-treated activated carbon 100 includes a crystalline structure 21 and an amorphous structure 11 , and the activated carbon 100 may have a crystalline structure 21 and an amorphous structure 11 mixedly present.

The amorphous structure 11 may include a plurality of pores 12 . Specifically, the amorphous structure 11 may include a plurality of pores 12 having a diameter D of 2 nm or less.

That is, the activated carbon 100 may include a plurality of pores. Accordingly, the pores 12 may exist in the electrode mixture layer 12 .

Activated carbon 100 according to the embodiment includes an amorphous structure 11 without a specific process as described above, but in order for the amorphous structure 11 to include a plurality of pores 12, an alkali activation treatment process described below is may be accompanied

More specifically, the heat-treated activated carbon may be activated with a material (activator) containing alkali at a temperature of 700 °C to 900 °C. In this case, the activated carbon and the alkali-containing activator may be mixed in a weight ratio of 1:1.5 to 1:4.

In the activation treatment step, a portion of the amorphous structure 11 may be broken to form pores 12 . In addition, the interlayer distance of the crystalline structure 21 formed in the heat treatment step of the activated carbon may be widened by the activation treatment (increase the interlayer distance from d1 to d2). Accordingly, the specific surface area of the activated carbon 100 may increase.

The pores 12 provide porosity to the activated carbon 100. The presence or absence of pores 12, the pore diameter (D) length of the pores 12, and the volume of the pores 12 having the corresponding diameter (D), etc. is a factor affecting the specific surface area of the activated carbon 100, details will be described later.

In the present specification, the diameter (D) of the pores 12 may mean, for example, the length of the vertical line when a vertical line is drawn from one pore internal region (I) to another pore internal region (I) to be described later. have. If the length of the vertical line is various, it may mean an average value of the length values.

The plurality of pores 12 may include a pore inlet 15 and an inner region I in communication with the pore inlet 15 .

Each of the plurality of pores 12 may have various shapes and various sizes.

According to an embodiment, the size of the pore inlet 15 may be adjusted by changing the temperature, treatment time, content of the activator, etc. in the heat treatment step and/or the activation treatment step of the activated carbon 100 .

The pore inlet 15 may include a pore inlet 15 that is smaller than the size of the first cation or the size of the first anion.

The inner region (I) may include an inner region (I) larger than the size of the first cation or the size of the first anion. Accordingly, the diameter (D) of the pores may be larger than the size of the first cation or the size of the first anion.

In the present specification, the size of the ion may mean the diameter of the ion.

Since the electrode material of the embodiment may include activated carbon 100 and a salt, the salt may be present in the inner region (I) of the pores.

The first solvent 16 may flow into the inner region I through the pore inlet 15 to dissociate the salt.

Accordingly, the salt existing in the pore internal region (I) may be dissociated by the first solvent 16 introduced into the pore inlet 15 to exist as the second ions 14 in the internal region (I). Accordingly, when the electrode is later impregnated with the electrolyte, the second ions 14 present in the pore inner region (I) may be adsorbed and desorbed from the pore inner region (I) during charging and discharging. Accordingly, the capacitance of the electric double layer capacitor may be significantly increased and high energy density may be realized.

In addition, since the first solvent 16 flows into the pore inner region I, wetting property is improved, and as the cell internal resistance is reduced, output characteristics of the electric double layer capacitor may be improved.

According to an embodiment, the pore inlet 15 may be larger than the size of the molecules of the first solvent 16 . In the present specification, the size of the solvent molecule may mean the diameter of the solvent molecule.

If the pore inlet 15 is larger than the size of the molecules of the first solvent 16, the first solvent 16 can easily flow into the pore internal region I, so that the salt present in the pore internal region I is transferred to the second It may be advantageous to dissociate to the ionic (14) state. Therefore, even if the physical specific surface area of the carbon source is not increased, the capacitance of the electric double layer capacitor is improved as the possibility of utilizing pores existing in the electrode is increased, and thus a high energy density can be realized.

According to an embodiment, the plurality of pores 12 may include pores 12 having a salt not dissociated by the first solvent 16 .

Activated carbon 100 according to the embodiment includes a plurality of pores 12 in the amorphous structure 11, and the length of the diameter D in the plurality of pores 12 is each pore 12. Each may be the same or different.

According to one embodiment, the activated carbon 100 may include pores 12 having the same length and diameter (D). According to another embodiment, the activated carbon 100 may include pores 12 having different lengths of diameters (D). According to another embodiment, the activated carbon 100 may include both pores 12 having the same diameter (D) and pores 12 having different diameters (D).

In the electric double layer capacitor of the embodiment, when the first ions 13 are inserted into the pores 12, the diameter D and/or the diameter of the pores 12 in consideration of the size of the first ions 13 ( The capacitance of the electric double layer capacitor may be improved by adjusting the volume ratio of the pores 12 having D).

The plurality of pores 12 present in the first electrode mixture layer and the second electrode mixture layer may have diameters D of various lengths. According to an embodiment, pores having the corresponding diameter (D) may be present in each of the first electrode mixture layer and the second electrode mixture layer.

In the present specification, the volume of the pores 12 may mean the volume of the pores 12 per unit mass of the electrode mixture layer [cm ³ /g].

In the electrochemical device of the embodiment, the volume of the pores 12 having a predetermined diameter D among the plurality of pores 12 may be adjusted in the manufacturing process of the electrode material. More specifically, by adjusting the alkali activation treatment temperature of the activated carbon 100, the type of material included in the electrode material, or the ratio of each material, the volume of the pores 12 having a certain diameter D among the pores 12 is reduced. can be adjusted.

The diameter D of the pores 12 is not set to a specific value and does not change, but is a value that can be changed within a certain range depending on the type of the activated carbon 100 and the conditions of the electrode material manufacturing process. Therefore, since the diameter (D) values of the pores 12 may exist within a certain range, in the present specification, the mode value (mode) of the diameter (D) of the pores 12 is the diameter (D) of the pores 12 . It may mean the value of the diameter (D) measured by the number of most cases among them.

According to an embodiment, the mode of the pore diameters of the first electrode mixture layer and the second electrode mixture layer may each independently be 0.5 nm or more and 1.2 nm or less. In this case, since the diameter D of the pores 12 is formed to match the size of the first ions 13 included in the electrolyte to be inserted into each electrode, a high energy density electrochemical device can be realized by securing high capacitance. It is preferable to be able to

According to an embodiment, the number of pores having a diameter (D) of 0.5 nm or more and 1.1 nm or less with respect to all pores 12 present in the electrode mixture layer may be 35% by volume to 85% by volume or less. In this case, it is preferable that the effect of improving the capacitance by adjusting the diameter of the pores 12 and the volume of the pores 12 can be maximized.

According to an embodiment, at least one of the first electrode mixture layer and the second electrode mixture layer has a mode value of the pore diameter ( mode) can be increased. Accordingly, in the electrode mixture layer, the farther away from the current collector 8, the smaller the amount of charge that the electrode mixture layer stands out, so that it is possible to prevent the problem of difficult insertion of ions into the pores, which is preferable.

The diameter (D) of the pores (12) and the volume of the pores (12) having the corresponding diameter (D) may be measured by the BET measurement method, but as long as they are within the scope not departing from the object of the present invention, it is not necessarily limited thereto. .

On the other hand, when the activated carbon 100 is activated, the crystal growth in the 002 direction may be dominant in the crystalline structure 21 , apart from the formation of pores 12 in the amorphous structure 11 . This leads to an increase in the proportion of the amorphous structure 11 and a decrease in the proportion of the crystalline structure 21 in the activated carbon 100 .

Meanwhile, in the crystalline structure 21 , the interlayer distance d may be controlled by an activation temperature and/or a content ratio of activated carbon and an activator.

If the weight ratio of the activated carbon to the activator is less than 1:1.5, the activated carbon cannot be sufficiently activated, so that the crystalline structure 21 having a sufficient interlayer distance for insertion of the first ions 13 may not be formed. In addition, when the weight ratio of the activated carbon to the activator exceeds 1:4, the distance between adjacent crystal layers increases, so that the van der Waals force between the crystal layers cannot act, so that the activated carbon 100 may lose crystallinity. In addition, if the weight ratio of the activated carbon to the activator is out of the above-mentioned range, it may be difficult to control the ratio of the pores 12 having the diameter D in a specific range.

Preferably, the activated carbon 100 and the activator may be mixed in a weight ratio of 1:1.5 to 1:3. More preferably, the activated carbon 100 and the activator may be mixed in a weight ratio of 1:1.7 to 1:3.

In addition, when the activation treatment temperature is less than 700 ° C. or exceeds 900 ° C., there is a problem in that it becomes difficult to control the proportion of pores 12 having a diameter D in a specific range.

Specific examples of the alkali material used in the activation treatment step may be lithium, sodium, potassium, etc., but is not necessarily limited thereto.

The activation treatment may be performed in an inert gas atmosphere. Specific examples of the inert gas may be helium, argon, nitrogen, etc., and may be used as an inert gas including at least one of the above-described examples, but is not necessarily limited thereto.

The interlayer distance (d) of the crystalline structure may be measured by a method widely known in the art, and specific examples thereof include X-ray diffraction analysis or TEM photography, but is not necessarily limited thereto.

According to an embodiment, the crystalline interlayer distance (d) may be 0.37 nm to 0.40 nm. If the crystalline interlayer distance d is less than 0.37 nm, the electrolyte ions 13 cannot be inserted between adjacent crystal lattice layers. In addition, if the interlayer distance (d) of the crystalline layer exceeds 0.40 nm, the distance between adjacent crystal layers increases, so that the van der Waals force existing between each crystal layer cannot act, and thus the crystallinity may be lost. Accordingly, when the crystalline interlayer distance (d) is out of the above range, there is a problem in that the capacitance (F/cc) is lowered.

As described above, the crystalline interlayer distance (d) may be controlled by the activation temperature and/or the content ratio of the activated carbon and the alkali activator.

The activated carbon 100 may include, for example, a material such as petroleum or coal-based pitch, raw coke (green coke), and calcination coke. Preferably, the activated carbon 100 may be petroleum-based or coal-based pitch activated carbon. However, as long as it is generally used in the art and does not deviate from the purpose of the present invention, the type of activated carbon 100 is not necessarily limited thereto.

According to one embodiment, the average particle size (D50) of the activated carbon 100 may be 6 μm or more and 8 μm or less. When the average particle size of the activated carbon 100 is within the range of 6 μm to 8 μm, the application process of the electrode material including the activated carbon 100 on the current collector may be easy.

On the other hand, the tap density may affect the capacitance. Specifically, when the tap density is too large, there is a problem in that the capacitance decreases, and when the tap density is too small, energy storage characteristics may be deteriorated.

In one embodiment, the tap density of the activated carbon 100 is 0.3 g/cm ³ to 0.65 g/cm ³ . If the tap density is a value within the above range, it is preferable because the electrostatic capacity of the activated carbon 100 increases.

After the activated carbon 100 and the alkali-containing activator are mixed and activated, a neutralization process may be performed to remove the alkali-containing material. Specific examples of the neutralizing agent used in the neutralization process may be hydrochloric acid, nitric acid, and the like.

Subsequently, the neutralized product may be subjected to a cleaning process.

The method for producing the activated carbon 100 is widely known in the art, and as long as it does not deviate from the purpose of the present invention, it may further include a corresponding process if necessary.

The electrode material according to the embodiment may include 50% by weight or more and 95% by weight or less of the activated carbon 100 based on 100% by weight of the total.

According to an embodiment, the second ion 14 may include both a second cation and a second anion.

Meanwhile, according to an embodiment, the second ion 14 may include two or more kinds of cations having different sizes, or the second anions may include two or more kinds of anions having different sizes. If necessary, the second cation 14 may include both cations of two or more cations having different sizes and two or more kinds of anions having different sizes. Both solubility of ions can be considered.

As a specific example of the second ion 14 , the cation included in the second ion 14 may be TMA ⁺ , TEA ⁺ , TBA ⁺ , TMEA ⁺ , TEMA ⁺ , SBP ^{+ ,} or the like. In addition, specific examples of the anions included in the second ion 14 may be BF ₄ ^- , TFSI ^- and CF ₃ SO ₃ ^- . Each of the second ions 14 may be used alone or in combination of two or more.

According to an embodiment, the size of the second ions 14 may be 0.450 nm or more and 0.830 nm or less.

According to an embodiment, the first ion 13 may include the same ion as the second ion 14 . That is, the second ion 14 may have the same type of ion as the first ion 13 .

Since the electric double layer capacitor of the embodiment can be treated with a continuous pressurization process during the manufacturing process, even the salt before dissociation into an ionic state as the second ion 14 of the same type and size as the first ion 13 is the electrode material of the embodiment It may be included in the pore and may be introduced into the inner region (I) of the pores. Accordingly, the effect of improving the usability of the pores 12 can be maximized.

According to an embodiment, the first ions 13 may include different ions from the second ions 14 . That is, the second ion 14 may have a different type of ion from the first ion 13 .

More specifically, the second ions 14 may have a smaller size than the first ions 13 , and in this case, the possibility of utilizing the pores 12 may be significantly improved.

Meanwhile, the second ion 14 may have a larger size than the first ion 13 . Even when the size of the ions of the second ions 14 is larger than that of the first ions 13 , if the solubility is excellent, the possibility of utilizing the pores 12 is improved, which may be advantageous in terms of capacitance.

The electrode material according to the embodiment may include 1 wt% or more and 10 wt% or less of the salt based on 100 wt% of the total.

In addition, the electrode material may further include a conductive material and a binder.

The binder imparts adhesion to the electrode material. Specific examples of the binder include carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP) and polyvinyl alcohol (PVA). The binder may be used including at least one of the above-described examples, but embodiments are not necessarily limited thereto.

According to an embodiment, the binder may be included in an amount of 1 wt% or more and 30 wt% or less based on 100 wt% of the total electrode material.

The conductive material imparts conductivity to the electrode material. Specific examples of the conductive material may be carbon black, graphene, carbon nanotubes (CNT), carbon nanofibers (CNF), and the like. The conductive material may be used including at least one of the above-described examples, but the embodiment is not necessarily limited thereto.

According to an embodiment, the conductive material may be included in an amount of 1 wt% or more and 30 wt% or less based on 100 wt% of the total electrode material.

If necessary, the electrode material may optionally further include a solvent. Specific examples of the solvent may be water or an organic solvent.

Specific examples of the solvent contained in the electrode material, AN (Acetonitrile), PC (Propylene Carbonate), SL (Sulfolane), ADN (Adiponitrile), etc. as the base solvent alone or in mixture of two or more types can be used.

In addition, optionally, EC (Ethylene Carbonate), DMC (Dimethyl Carbornate), EMC (Ethyl Methyl Carbonate), DMS (Dimethyl Sulfone), EMS (Ethyl Methane Sulfonate), etc. may be mixed and used as an additional solvent in the base solvent.

The solvent included in the electrode material may be used in a trace amount within a range that does not deviate from the purpose of the embodiment.

Each component of the electrode material of the above-described embodiment may be mixed. The mixing method may not be particularly limited as long as it does not deviate from the purpose of the embodiment.

According to an embodiment, the electrode mixture layer 9 may be formed by rolling the electrode material on the current collector 8 after mixing the electrode material. According to another embodiment, the electrode mixture layer 9 may be formed by coating the electrode material on the current collector 8 . According to another embodiment, the electrode mixture layer 9 may be formed by making an electrode material in a sheet state, attaching it to the current collector 8 , and then drying the electrode material. In addition, it may be applied on the current collector 8 in the form of a slurry after mixing each component of the electrode material, but the present invention is not necessarily limited to the embodiments.

Subsequently, the prepared electrode mixture layer 9 may be dried and pressurized.

A specific example of the pressing process may be a cold press and/or a hot press by a kneading method, and the salt contained in the electrode material is more in the inner region (I) of the pores by the pressing process can be effectively introduced.

In the electric double layer capacitor of the embodiment, when a current flows through the current collector 8, the electrode mixture layer 9 becomes charged, and the first ions 13 move to the electrode having a charge opposite to the charge of the ion. An electric double layer can be formed at the interface of each electrode. For a specific example, the first anions move to the interface of the first electrode 2 and the first cations move to the interface of the second electrode 4, and among the first ions 13, the size of the pore inlet 15 is larger than that of the first ions 13. If the size of the ions is small, they may be located in the inner region I of the pores of the activated carbon 100 present in the electrode mixture layer 9 of each of the electrodes 2 and 4 .

According to an embodiment, the specific surface area of the activated carbon 100 may be 400 m ² /g or more and 900 m ² /g or less. When the specific surface area of the pores of the activated carbon 100 is within the above range, the first ions 13 can easily flow between the crystal lattices of the crystalline structure 21 or into the pores 12 of the amorphous structure 11, so that the electrostatic capacity This can be significantly improved. That is, if the specific surface area of the activated carbon 100 is ^{less than 400 m 2} /g, the diameter D of the pores 12 is smaller than that of the first ions 13, so that the first ions 13 may not be inserted. In addition, when the specific surface area of the activated carbon 100 ^{exceeds 900 m 2} /g, the capacitance may decrease.

The specific surface area may be measured by a BET measurement method, but is not necessarily limited thereto.

According to an embodiment, lead wires 6 and 7 may be attached to each of the first electrode 2 and the second electrode 4 . In addition, the first electrode 2 , the second electrode 4 , and the separator 3 disposed therebetween may have a structure disposed in the cover 5 .

According to one embodiment, the cover 5 may be formed to include a conductive material. The conductive material may include a metal or the like. A specific example of the metal may be aluminum or the like.

Hereinafter, the action and effect according to the present invention will be described in more detail through specific examples and comparative examples.

Example

The residual oil from the Naphta Cracking Center (NCC) process was heat-treated at a temperature of 350° C. to make a solid pitch with a molecular weight ranging from 1000 to 2500 and used as activated carbon.

Activated carbon 1 prepared by the above method was heat-treated at a hot spot of 60 Φ * 120 cm for 1 hour at a temperature of 750° C. under an argon atmosphere.

Then, activated carbon 1 was activated by setting the content ratio of activated carbon 1 and KOH activator to 1:3 under an argon atmosphere at 750° C. for 2 hours.

85% by weight of the activated carbon, 5% by weight of the binder, 5% by weight of the conductive material. After preparing an electrode material by mixing TEABF ₄ 5 wt%, the electrode material was pressed with a roller on a current collector of aluminum foil to make a sheet state, and then dried to prepare a positive electrode.

comparative example

A supercapacitor was manufactured in the same manner as in Example except that _{TEABF 4 salt was not included.}

Experimental example : Initial capacitance evaluation

The capacitance per unit volume at 0.565 mA was measured with a Hi-EDLC 16CH instrument (manufactured by Human Instruments), and the results are shown in Table 4 below.

division
[F/cc] Example comparative example 1 time 28.8 27.6 Episode 2 29.1 27.5 3rd time 28.1 26.8

Referring to Table 4, it was confirmed that the electric capacitor of the example including the salt exhibited a higher capacitance value than that of the comparative example.

The energy density can be calculated by Equation 1 below,

[Equation 1]

Energy density (E) = {capacitance (C)}*{operating voltage (V)} ² /2

It could be predicted that the Example could implement a higher energy density than the Comparative Examples.

In the electric double layer capacitor of the embodiment, the second ions 14 dissociated from the salt by the first solvent 16 introduced into the internal region I of the pore through the pore inlet 15 in the internal region I of the pore 14 may include The second ions 14 may be adsorbed and desorbed in the inner region I of the pores during charging and discharging. Therefore, even if the physical specific surface area of the activated carbon 100 is not increased, the utilization possibility of the pores 12 present in the electrode is improved, and thus, the high capacitance and high energy density of the electric double layer capacitor may be realized.

In addition, the output characteristics of the electric double layer capacitor can be improved by reducing the cell internal resistance according to the improvement of the wettability.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

100: activated carbon 10: electric double layer capacitor
11: amorphous 12: pores
13: first ion 14: second ion
15: pore inlet 16: first solvent
21: crystalline d: crystalline interlayer distance
1: first separator 2: first electrode
3: second separator 4: second electrode
5: Cover 6: First lead wire
7: second lead wire 8: current collector
9: electrode mixture layer
D: diameter of pores
I: the inner region of the pore
d: crystalline interlayer distance

Claims (9)

a first electrode;
a second electrode spaced apart from the first electrode;
a separator disposed between the first electrode and the second electrode; and
including; an electrolyte impregnating the first electrode, the second electrode, and the separator;
The first electrode and the second electrode each include a current collector and an electrode mixture layer disposed on at least one surface of the current collector,
The electrolyte includes a first ion and a first solvent,
The first ion comprises a first cation and a first anion,
The electrode mixture layer includes activated carbon and a salt,
The activated carbon includes a plurality of pores,
wherein the salt is disposed inside at least one of the pores;
wherein the plurality of pores includes a pore inlet and an interior region in communication with the pore inlet;
The pore inlet includes a pore inlet smaller than the size of the first cation or the size of the first anion,
The inner region includes the inner region larger than the size of the first cation or the size of the first anion,
The first solvent flows into the inner region through the pore inlet to dissociate the salt.
The method according to claim 1,
The salt is dissociated by the first solvent introduced into the pore inlet and exists as a second ion.
The method according to claim 1,
The plurality of pores, including pores having a salt not dissociated by the first solvent, electric double layer capacitor.
3. The method according to claim 2,
wherein the second ion includes both a second cation and a second anion.
5. The method according to claim 4,
The second cation includes two or more cations having different sizes, or the second anion includes two or more kinds of anions having different sizes.
5. The method according to claim 4,
and the first ion comprises the same ion as the second ion.
3. The method according to claim 2,
The second ion is TMA ⁺ , TEA ⁺ , TBA ⁺ , TMEA ⁺ , TEMA ⁺ , SBP ⁺ , BF ₄ ^- , TFSI ^- and CF ₃ SO ₃ ^- Electric double layer capacitor comprising at least one selected from the group consisting of .
The method according to claim 1,
With respect to all pores present in the electrode mixture layer
An electric double layer capacitor, wherein the pores having a diameter (D) of 0.5 nm or more and 1.1 nm or less are 35% by volume or more and 85% by volume or less.
delete

Images