KR102239685B1 - Electro-conductive adhesive using activated carbon, electrode current collector, electrode for supercapacitor and the supercapacitor having improved high temperature performance - Google Patents

Abstract

The present invention relates to a conductive adhesive that enhances adhesion at high temperatures by using activated carbon, which is cheaper than graphene and carbon nanotubes that have been conventionally used, and an electrode current collector formed by applying the conductive adhesive to a high-purity aluminum surface. , A supercapacitor electrode formed by coating a slurry composed of a mixture of activated carbon, a conductive material, and a binder on the surface of the electrode current collector, and a supercapacitor having excellent performance at high temperature by using the electrode for the supercapacitor It is about.

Description

Conductive adhesive made of activated carbon, electrode current collector using it, electrode for supercapacitor, and supercapacitor with excellent high-temperature performance {ELECTRO-CONDUCTIVE ADHESIVE USING ACTIVATED CARBON, ELECTRODE CURRENT COLLECTOR, ELECTRODE FOR SUPERCAPACITOR AND THE SUPERCAPACITOR HAVING IMPROVED HIGH TEMPERATURE}

The present invention relates to a conductive adhesive that enhances adhesion at high temperatures by using activated carbon, which is cheaper than graphene and carbon nanotubes that have been conventionally used, and an electrode current collector formed by applying the conductive adhesive to a high-purity aluminum surface. , A supercapacitor electrode formed by applying a slurry composed of a mixture of activated carbon, a conductive material, and a binder on the surface of the electrode current collector, and a supercapacitor having excellent high-temperature performance by using the electrode for the supercapacitor. will be.

Recently, in the ubiquitous era where IT technology is becoming more common and more common, home appliances, electronic devices, and logistics are becoming smarter, and the reliability of the devices has emerged the most.

It is the surrounding environment of each device that has the greatest impact on this reliability. In particular, as the warming phenomenon is getting worse, the performance improvement at high temperature is in the spotlight.

In order to secure high reliability in such devices and systems, an energy storage device having a long life even at high temperatures is required.

As an energy storage device that can meet this condition, a supercapacitor is suitable. The reason is that a supercapacitor has a lower operating voltage than a lithium secondary battery, but can be used at a high temperature and has a long lifespan.

However, if such a supercapacitor is used for a long time at a high temperature, the existing lifespan is shortened, and the ability as a supercapacitor having a long life is lost.

In order to achieve excellent long-term performance even at high temperatures, it is necessary to approach and solve the problem from various perspectives, such as electrodes, electrolytes, and accessories, and among them, cases of applying conductive adhesives to improve the problem of electrode detachment at high temperatures are increasing.

However, graphene and carbon nanotubes, which are the main materials used in the production of the conductive adhesive, have a high cost and are difficult to produce.

In order to solve such a problem, the present invention develops a conductive adhesive using activated carbon, which is cheaper than graphene and carbon nanotubes, and provides an electrode for a supercapacitor and a supercapacitor with improved high temperature performance using the conductive adhesive. I want to.

Korean Patent Registration 10-0581232 (Registration Date 2006.05.11) Korean Patent Registration 10-1162464 (Registration Date 2012.06.27) Korean Patent Registration 10-1381956 (Registration Date 2014.03.31) Republic of Korea Patent Publication 10-2014-0095475 (Publication date 2014.08.01)

To solve the above problem,

The present invention is a conductive adhesive that enhances adhesion at high temperatures using activated carbon, which is cheaper than graphene and carbon nanotubes, an electrode current collector formed by applying the conductive adhesive to a high-purity aluminum surface, and activated carbon, a conductive material. And a supercapacitor electrode formed by applying a slurry composed of a mixture of a binder on the surface of the electrode current collector, and the supercapacitor electrode, thereby providing a supercapacitor having excellent high-temperature performance. The purpose.

In order to achieve the above object, the present invention provides the following.

first. 2.0 to 9.0 wt% activated carbon; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mix 80.0 ~ 90.0 wt% of distilled water to form a dispersion,

5.0 to 15.0 wt% of the composition dispersion; Epoxy resin binder 10.0 to 20.0 wt%; It provides a conductive adhesive made of activated carbon composed of a mixture of 65.0 ~ 80.0 wt% of distilled water.

second. An electrode current collector manufactured by applying the conductive adhesive to a thickness of 0.5 to 5.0 µm on an aluminum surface is provided.

third. 80.0 to 90.0 wt% of activated carbon having an average particle size of 10.0 to 15.0 µm; 5.0 to 15.0 wt of any one or two or more conductive materials selected from carbon black, hard carbon, soft carbon, graphite, carbon nano tube %; 3.0 to 8.0 wt% of any one or two or more binders selected from carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), and polytetrafluoroethylene (PTFE); to prepare a slurry,

It provides an electrode for a supercapacitor manufactured by applying the slurry to the surface of the electrode current collector.

fourth. After arranging the electrodes for the supercapacitor of claim 4 on both sides of the separator, the electrode for a supercapacitor of claim 4 is arranged and rolled into a cylindrical shape to manufacture a wound-up device, and the wound-up device is dried at 125 to 135° C. for 45 to 53 hours, and the dried wound-up device Is impregnated in the electrolyte for 15 to 25 minutes, and then the impregnated wound element is put in an aluminum can and sealed to provide a supercapacitor made of a cell.

The conductive adhesive made of activated carbon according to the present invention, an electrode current collector using the same, an electrode for a supercapacitor, and a supercapacitor have the following effects.

first. The conductive adhesive made of the activated carbon of the present invention has a small capacity and resistance change rate of the cell at high temperature, as confirmed through FIGS. 3 and 4. This means that the conductive adhesive proposed in the present invention has excellent stability at high temperatures.

second. Unlike graphene, activated carbon has a non-uniform particle size and shape, and as a result, the surface energy of a surface coated with a conductive adhesive made of activated carbon is increased, and thus has a property of improving adhesion at high temperatures.

third. By using inexpensive activated carbon in place of expensive graphene and carbon nanotubes that have been generally used in the manufacture of conventional conductive adhesives, the manufacturing cost according to cost reduction can be lowered, and thus price competitiveness is excellent.

fourth. The present invention provides an improved supercapacitor electrode and supercapacitor capable of maintaining long-life characteristics even in a high-temperature state by using a conductive adhesive made of activated carbon.

1 is a schematic diagram of an electrode for a supercapacitor according to the present invention.
2 is a graph showing the results of high temperature durability evaluation of a supercapacitor manufactured according to Example 4 of the present invention.
3 is a graph showing the rate of change in resistance (AC-ESR) over time of a supercapacitor manufactured according to Example 4 of the present invention.

Hereinafter, a detailed description of a conductive adhesive made of activated carbon according to the present invention, an electrode current collector using the same, an electrode for a supercapacitor, and a supercapacitor will be described.

[Conductive adhesive]

As mentioned above,

The conductive adhesive made of activated carbon according to the present invention has improved performance at high temperatures,

2.0 to 9.0 wt% activated carbon; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mix 80.0 ~ 90.0 wt% of distilled water to form a dispersion,

5.0 to 15.0 wt% of the composition dispersion; Epoxy resin binder 10.0 to 20.0 wt%; It is composed by mixing 65.0 to 80.0 wt% of distilled water;

The activated carbon constituting the dispersion has a function of improving conductivity, and when the amount is less than 2.0 wt%, the improvement in conductivity is insignificant, and when it exceeds 9.0 wt%, it is difficult to manufacture as a dispersion, and the amount of the activated carbon is used. It is limited within the range of 2.0 to 9.0 wt% based on the total weight of the silver dispersion.

In addition, the activated carbon is used having an average particle size of 1.0 to 2.0 µm and a specific surface area of 800 to 1,000 ㎡/g.

The dispersant of the polycarboxylic acid has a dispersing function by lowering the cohesive strength between activated carbons, and is limited to 3.0 to 15.0 wt% of the total weight of the dispersion in order to adjust the viscosity according to the amount of activated carbon.

The amount of distilled water is determined according to the ratio of the activated carbon and the polycarboxylic acid, and the amount of distilled water is limited to 80.0 to 90.0 wt% based on the total weight of the dispersion.

Specific mixing examples of the dispersion are shown in Table 1 below.

Formulation example 1 Formulation example 2 Formulation example 3 Formulation Example 4 Formulation Example 5 Activated carbon 2.0 wt% 4.0 wt% 6.0 wt% 7.0 wt% 9.0 wt% Poly
Carboxylic acid 15.0 wt% 12.0 wt% 10.0 wt% 5.0 wt% 3.0 wt% Distilled water 83.0 wt% 84.0 wt% 84.0 wt% 88.0 wt% 88.0 wt% Sum 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt%

The conductive adhesive according to the present invention is formulated by mixing the above-described dispersion, an epoxy resin binder, and distilled water.

The dispersion is used in a range of 5.0 to 15.0 wt%, based on the total weight of the conductive adhesive, to allow uniform blending between components.

If the amount of the dispersion is less than 5.0 wt%, the conductivity improvement is insignificant, and if it exceeds 15.0 wt%, the stability of the dispersion decreases and the storage period is shortened. It is preferable to limit it within the range of 5.0 to 15.0 wt% based on the total weight.

The epoxy resin binder has a function of enhancing the dispersibility of the activated carbon used in the dispersion and improving adhesion to the current collector during coating. It is used within the range of 10.0 to 20.0 wt% based on the total weight of the conductive adhesive.

When the amount of the epoxy resin binder is less than 10.0 wt%, there is a problem that the adhesive strength decreases, and when it exceeds 20.0 wt%, it is difficult to control the appropriate thickness during coating due to high viscosity, and the amount of the epoxy resin binder is conductive. It is preferable to limit it within the range of 10.0 to 20.0 wt% based on the total weight of the adhesive.

The amount of distilled water is determined according to the ratio of the dispersion and the epoxy resin binder, and is used within the range of 70.0 to 80.0 wt% based on the total weight of the conductive adhesive.

Specific mixing examples of the conductive adhesive are shown in Table 2 below.

Formulation example 1 Formulation example 2 Formulation example 3 Formulation Example 4 Formulation Example 5 Dispersion 5.0 wt% 7.0 wt% 10.0 wt% 13.0 wt% 15.0 wt% Epoxy resin 15.0 wt% 16.0 wt% 18.0 wt% 19.0 wt% 20.0 wt% Distilled water 80.0 wt% 77.0 wt% 72.0 wt% 68.0 wt% 65.0 wt% Sum 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt%

[Electrode current collector]

The electrode current collector according to the present invention is manufactured by applying the conductive adhesive to an aluminum surface with a thickness of 0.5 to 5.0 μm.

The coating thickness of the conductive adhesive affects the conductivity of the electrode and the adhesion between the activated carbon and the current collector. When the thickness is less than 0.5 µm, it is difficult to properly coat, and when it exceeds 5.0 µm, it is relatively active carbon. Since there is a problem in that the electrode layer becomes thin and the rated capacity (F) is lowered, the coating thickness of the conductive adhesive is preferably limited within the range of 0.5 to 5.0 μm.

[Electrode for supercapacitor]

The supercapacitor electrode according to the present invention is prepared by applying a slurry composed of a mixture of activated carbon, a conductive material, and a binder on the surface of the electrode current collector.

The slurry includes 80.0 to 90.0 wt% of activated carbon having an average particle size of 10.0 to 15.0 µm; 5.0 to 15.0 wt of any one or two or more conductive materials selected from carbon black, hard carbon, soft carbon, graphite, carbon nano tube %; Carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE) any one or two or more binders selected from 3.0 to 8.0 wt%; is a mixture of the composition. The slurry is applied to a thickness of 130 to 180 µm on the surface of the electrode current collector.

Specific mixing examples of the slurry are shown in Table 3 below.

Formulation example 1 Formulation example 2 Formulation example 3 Formulation Example 4 Formulation Example 5 Dispersion 80.0 wt% 82.0 wt% 85.0 wt% 87.0 wt% 90.0 wt% Epoxy resin 15.0 wt% 13.0 wt% 9.0 wt% 7.0 wt% 5.0 wt% Distilled water 5.0 wt% 5.0 wt% 6.0 wt% 6.0 wt% 5.0 wt% Sum 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt% 100.0 wt%

1 is a schematic diagram showing the structure of a supercapacitor electrode according to the present invention, an electrode current collector 10, a conductive adhesive 20 applied on the surface of the electrode current collector 10, and the conductive adhesive 20 It is shown that the slurry 30 to be re-applied is integrated in a stacked structure.

[Super capacitor]

The supercapacitor according to the present invention has excellent stability in use even at high temperatures, and after disposing the electrodes for the supercapacitor proposed in the present invention on both sides based on the separator, the supercapacitor according to the present invention is rolled into a cylindrical shape to manufacture a wound element, and the wound element After drying at 125 to 135° C. for 45 to 53 hours, the dried winding element was impregnated in an electrolytic solution for 15 to 25 minutes, and then the impregnated wound element was put into an aluminum can and sealed to form a cell.

In addition, the cell is manufactured in a dry room in which moisture is maintained at 30 ppm or less from drying of the wound device.

That is, from the process of drying the wound element at 125 ~ 135 ℃ for 45 ~ 53 hours to the process of manufacturing the impregnated wound type element into an aluminum can and sealing it into a cell, it is made in a dry room maintained at 30 ppm or less.

Hereinafter, specific details of the conductive adhesive according to the present invention, an electrode current collector using the same, an electrode for a supercapacitor, and a supercapacitor will be described with examples.

[Manufacture of conductive adhesives]

A dispersion was prepared by mixing 5.0 wt% of activated carbon having an average particle size of 2.0 µm, 10.0 wt% of a polycarboxylic acid dispersant, and 85.0 wt% of distilled water.

10.0 wt% of the dispersion, 15.0 wt% of an epoxy resin binder, and 75.0 wt% of distilled water are mixed to prepare a final conductive adhesive.

[Comparative Example 1]

It was prepared in the same manner as in Example 1, but a conductive adhesive was prepared using graphene instead of activated carbon.

[Creator manufacturing]

A new current collector was manufactured by applying the conductive adhesive prepared in Example 1 to the aluminum surface. At this time, the coating thickness of the conductive adhesive is 5 μm.

[Comparative Example 2]

The conductive adhesive prepared in Comparative Example 1 was applied to the aluminum surface to prepare a new current collector. At this time, the coating thickness of the conductive adhesive is 5 μm.

[Comparative Example 3]

An aluminum current collector without a conductive adhesive is used as it is.

[Manufacture of electrodes for super capacitors]

A slurry was prepared by mixing 85.0 wt% of activated carbon (CEP17) having an average particle size of 13.0 µm, 10.0 wt% of a conductive material (Super-P), and 5.0 wt% of a binder (CMC/SBR). The slurry was applied on the current collector prepared in Example 2 to prepare an electrode for a supercapacitor.

[Comparative Example 4]

An electrode was manufactured by applying the slurry prepared in Example 3 onto the current collector prepared in Comparative Example 2.

[Comparative Example 5]

The slurry prepared in Example 3 was coated on the current collector of Comparative Example 3 to prepare an electrode.

[Super capacitor manufacturing]

A super capacitor is manufactured, but electrodes are arranged on both sides of the separator in order to be manufactured in a radical type,

The electrodes shown in Example 3, Comparative Example 4, and Comparative Example 5 were respectively disposed and then rolled into a cylindrical shape to prepare three different winding-type devices.

Next, in order to remove moisture from the wound device, it is dried at 130° C. for 48 hours.

Then, the dried winding element is _{impregnated in 1M TEABF 4} /AN electrolyte for 20 minutes, and the impregnated wound element is put into an aluminum can of 10 × 30 mm and sealed to form a cell.

At this time, the entire process from drying of the wound-type device to manufacturing into a cell by putting it in a can is performed in a dry room where moisture is maintained at 30 ppm or less.

[Super capacitor evaluation]

[Test Example 1]

<Capacity and resistance evaluation>

Each cell prepared in Example 4 was conducted with a constant current-constant voltage in order to check the charging/discharging characteristics. At this time, the current was evaluated as 100 mA (Table 4).

Current collector composition Power storage capacity (F) DC-ESR(mΩ) AC-ESR(mΩ) Activated carbon-conductive adhesive
/ Aluminum current collector 10.05 26.55 14.34 Graphene-conductive adhesive
/ Aluminum current collector 10.04 26.32 14.22 Aluminum current collector 10.35 27.81 15.58

[Test Example 2]

<High temperature durability evaluation>

In order to carry out high-temperature durability evaluation, the experiment is conducted with a constant current of 2.7 V in a heating cabinet at 85°C, and according to time, the cell is removed from the heating cabinet and left at room temperature for about 30 minutes to thermally level the cell for evaluation. At this time, the evaluation criteria follow Example 4.

2 is a graph showing high temperature durability evaluation results of a supercapacitor manufactured according to Example 4 of the present invention.

2(a) and (b) show the change in capacity over time, where (a) is the actual capacity, and (b) shows (a) calculated as a percentage.

The evaluation result shown in FIG. 2 is the capacity obtained by charging and discharging the cell by carrying out a constant current of 2.7 V in a chamber at 85° C. and taking the cell out of the heating cabinet over time.

3 is a graph showing a change rate of resistance (AC-ESR) over time of a supercapacitor manufactured according to Example 4 of the present invention.

3A and 3B show changes in AC-ESR over time, where (a) is an actual AC-ESR, and (b) shows (a) calculated as a percentage.

The evaluation result shown in FIG. 3 is an AC-ESR measured by carrying out a constant current of 2.7 V in a chamber at 85° C. and taking the cell out of the heating cabinet over time.

The present invention uses inexpensive activated carbon in place of expensive graphene and carbon nanotubes generally used in the manufacture of conventional conductive adhesives, thereby lowering the manufacturing cost according to cost reduction, increasing price competitiveness, and improving performance under high temperature conditions. It has great industrial applicability by providing a supercapacitor electrode and a supercapacitor.

10: electrode current collector 20: conductive adhesive
30: slurry

Claims (7)

2.0 to 9.0 wt% of activated carbon having an average particle size of 1.0 to 2.0 µm and a specific surface area of 800 to 1,000 ㎡/g; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mixing 80.0 to 90.0 wt% of distilled water to form a dispersion,
5.0 to 15.0 wt% of the composed dispersion; Epoxy resin binder 10.0 to 20.0 wt%; Conductive adhesive made of activated carbon, characterized in that consisting of a mixture of distilled water 70.0 ~ 80.0 wt%;
delete 2.0 to 9.0 wt% of activated carbon having an average particle size of 1.0 to 2.0 µm and a specific surface area of 800 to 1,000 ㎡/g; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mixing 80.0 to 90.0 wt% of distilled water to form a dispersion,
5.0 to 15.0 wt% of the composed dispersion; Epoxy resin binder 10.0 to 20.0 wt%; An electrode current collector manufactured by applying a conductive adhesive comprising a mixture of 70.0 to 80.0 wt% of distilled water to an aluminum surface with a thickness of 0.5 to 5.0 µm.
80.0 to 90.0 wt% of activated carbon;
5.0 to 15.0 wt of any one or two or more conductive materials selected from carbon black, hard carbon, soft carbon, graphite, carbon nano tube %;
Carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE) any one or two or more binders selected from 3.0 to 8.0 wt%; mixing to prepare a slurry,
As prepared by applying the slurry to the surface of an electrode current collector,
The electrode current collector has an average particle size of 1.0 to 2.0 µm and a specific surface area of 2.0 to 9.0 wt% of activated carbon with a specific surface area of 800 to 1,000 ㎡/g; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mixing 80.0 to 90.0 wt% of distilled water to form a dispersion,
5.0 to 15.0 wt% of the composed dispersion; Epoxy resin binder 10.0 to 20.0 wt%; An electrode for a supercapacitor, characterized in that it is manufactured by applying a conductive adhesive composed of a mixture of distilled water of 70.0 to 80.0 wt%; to an aluminum surface with a thickness of 0.5 to 5.0 µm.
The method of claim 4,
The activated carbon contained in the slurry has an average particle size of 10.0 to 15.0 µm.
After arranging the supercapacitor electrodes on both sides of the separation membrane as a reference, the winding-type element was manufactured by rolling it into a cylindrical shape, and the wound-type element was dried at 125-135° C. for 45-53 hours, and the dried wound-type element was placed in an electrolyte solution. After impregnating for 15 to 25 minutes, the impregnated winding element was put in an aluminum can and sealed to form a cell.
The electrode for the supercapacitor is activated carbon 80.0 ~ 90.0 wt%;
5.0 to 15.0 wt of any one or two or more conductive materials selected from carbon black, hard carbon, soft carbon, graphite, carbon nano tube %;
Carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE) any one or two or more binders selected from 3.0 to 8.0 wt%; mixing to prepare a slurry,
It is prepared by applying the slurry to the surface of an electrode current collector,
The electrode current collector has an average particle size of 1.0 to 2.0 µm and a specific surface area of 2.0 to 9.0 wt% of activated carbon with a specific surface area of 800 to 1,000 ㎡/g; 3.0 to 15.0 wt% of a dispersant of polycarboxylic acid; Mixing 80.0 to 90.0 wt% of distilled water to form a dispersion,
5.0 to 15.0 wt% of the composed dispersion; Epoxy resin binder 10.0 to 20.0 wt%; A supercapacitor, characterized in that it is manufactured by applying a conductive adhesive composed of a mixture of distilled water of 70.0 to 80.0 wt%; to an aluminum surface with a thickness of 0.5 to 5.0 µm.

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