KR101166148B1 - A method of current collector with cubic pattern by photolithography and a capacitor using thereof - Google Patents

Abstract

PURPOSE: A method for manufacturing an aluminum current collector having a three-dimensional pattern structure using photolithography and a method for manufacturing an ultra-high capacity capacitor comprising the aluminum current collector are provided to effectively increase the contact area between an aluminum current collector and an active material. CONSTITUTION: A method for manufacturing an aluminum current collector having a three-dimensional pattern structure comprises the steps of: washing and drying an aluminum foil current collector, spreading a photoresist solution on the surface of the aluminum foil current collector, spreading a development solution on the entire surface of the aluminum current collector, etching the aluminum foil current collector, and washing and drying the etched aluminum foil current collector.

Description

A method of manufacturing an aluminum current collector having a three-dimensional pattern structure using photolithography and a method of manufacturing an ultracapacitor including the same {A method of current collector with cubic pattern by photolithography and a capacitor using approx}

The present invention relates to a method of manufacturing an aluminum current collector (Current Collector) having a three-dimensional pattern (Pattern) structure using photolithography, and to an ultra-capacitor containing the same, and more specifically to photolithography After designing a certain pattern on the surface of the aluminum current collector using the method and selectively etching them to form a three-dimensional pattern structure on the surface of the aluminum current collector to increase the surface area and aluminum current collector having this three-dimensional pattern (Pattern) structure It relates to a supercapacitor made by applying.

Due to rising oil prices and global warming issues, technologies in the field of alternative energy are attracting attention, and among them, the technology of energy storage devices has been rapidly developed, led by lithium ion secondary batteries. However, supercapacitors are being used as an alternative to secondary batteries, which are limited in applications requiring high power due to their high electrical capacity but low output. Increasingly, the scope of application to the secondary battery area is gradually expanded. In particular, the ultra-capacitor capacitor is easier to utilize the regenerative braking energy than the secondary battery, which is difficult to utilize the regenerative braking energy, and is currently being applied to more and more various fields.

Ultracapacitors use activated carbon with a large surface area to repeat charging and discharging by using physical adsorption and desorption reactions of ions in the electrolyte. By doing so, the electrical capacity could be dramatically improved. In addition, recently, concepts such as ultracapacitor capacitors in which one or both electrodes are replaced with activated carbon by using metal oxides or carbon nanotubes (CNT), carbon nanofibers (CNF), and composite metal oxides have emerged. Is going higher.

Aluminum foil in ultracapacitors acts as a current collector to guide electrons transferred from activated carbon to an external circuit, and minimizes the resistance that occurs when electrons are transferred from activated carbon to the current collector. There is a demand for interfacial properties. To this end, by increasing the contact area with the active material by etching the surface of the current collector by an electrochemical method, the equivalent series resistance (ESR) of the ultracapacitor applied to it can be lowered. By applying nickel foam as a current collector to improve the contact area between the active material and the current collector, research has been conducted to realize not only the ESR of the supercapacitor applied thereto but also an increased effective capacity. The commercialization of the applied ultracapacitor has a practical problem.

In addition, the conventional method for increasing the electrical capacity of the ultra-capacitor capacitor is to replace the active material with a metal oxide of the redox reaction instead of the activated carbon in the physical adsorption and desorption reaction, or carbon nanotubes (CNT) having a larger surface area than the activated carbon The method of using an active material like this, etc. are mentioned. This method of substituting the active material has the problem that the first active material is not produced in large quantities or some of the materials that are being produced cannot use the process equipment manufactured using the activated carbon as it is. It is very high and has many problems in terms of cost.

       In addition, the electrochemical etching method of the aluminum current collector using the current electrolyte alone may increase the contact area between the active material and the aluminum current collector to increase the effective capacity of the ultracapacitor. I can't do it.

An object of the present invention is to solve the above problems of the prior art, by using a photolithography (Photolithography) to form a pattern (Pattern) on the surface of the existing aluminum current collector (aluminum current collector through their selective etching) The present invention provides a method for manufacturing an aluminum current collector by effectively increasing the contact area between an active material and an active material, and by applying such a current collector, an ultra-high capacity capacitor having an effective capacity while using an existing active material as it is.

The present invention to achieve the above object of the present invention;

Washing the aluminum foil current collector and then drying with nitrogen (S1);

Applying a photoresist on the surface of the dried aluminum foil current collector and then drying the photoresist to selectively expose the photoresist to be cured (S2);

After the step (S2) by spraying the developer on the exposed aluminum current collector to selectively remove the unexposed photoresist and completely curing the remaining photoresist to complete the formation of a pattern on the aluminum current collector (S3);

Placing two carbon plates as opposite electrodes, and placing a patterned aluminum foil current collector between the two carbon plates to apply an AC power source and primary etching the aluminum current collector in the electrolyte (S4);

Drying the etched aluminum current collector (S5);

After the step (S5) and the second carbon plate as a counter electrode, and the primary etching after the secondary etching by placing the dried aluminum current collector between the opposite electrodes (S6); And

It provides a method for producing an aluminum current collector having a three-dimensional pattern structure characterized in that it comprises a step (S7) of washing and drying the secondary etched aluminum foil.

In the above step (S1) of the aluminum foil is preferably 99.00 ~ 99.99% purity and the thickness of 10 ~ 100㎛ used, if the purity is lower than 99.00 EDLC leakage current characteristics worse, 100% pure aluminum Since foil cannot be manufactured by current technology, the depth that can be etched must be limited to less than 10 μm when the thickness is less than 10 μm. When the depth of etching is low, the effect of the invention is lowered, and the thickness exceeds 100 μm. This can lead to the adverse effect of increasing the volume of the electrode, which in turn reduces the energy density.

In addition, the photoresist coating in the step (S2) is preferably carried out with a thickness of 0.5 ~ 50㎛, if the thickness of the photoresist coating is less than 0.5㎛ the photoresist is easily broken when the current collector is etched, the pattern collapses due to excessive etching, 50㎛ If the thickness is too thick, it is difficult to penetrate the etching solution and thus may not be sufficiently etched to form the pattern completely, and the drying in the step (S2) is 5 to 5 at a temperature of 50 to 150 ° C. If the drying temperature is above 150 ° C, the photoresist is destroyed. If the drying temperature is lower than 50 ° C, it takes a long time to cure the photoresist, which is not practical. The pattern can easily collapse during the process, and over 30 minutes, even with selective curing with excessive curing, Gwanghan is because the pattern can not be formed correctly.

In addition, the exposure in the step (S2) is selectively performed by placing a mask in the shape of a pattern made of chromium on a transparent material on an aluminum current collector coated with a photosensitive liquid and then irradiating UV light, wherein the mask is quartz UV light-transmitting material is used, and the mask has a shape of 10 to 500 μm in size and a pattern of 10 to 500 μm in combination. The size and spacing of the pattern shape is less than 10 μm or more than 500 μm. If it becomes large, the effect of shortening the moving distance of electrons moving from the active material to the current collector may appear, so that the effect of the invention may be lowered as described above.

In addition, the photosensitive liquid in the step (S3) using an acid or an alkaline solution except neutral, the curing in the step (S3) is carried out for 5 to 60 minutes at a temperature of 50 ~ 150 ℃ but the drying temperature is 150 ℃ When the photoresist is destroyed above 50 ° C, the photoresist is too much time to cure the photoresist, and when the drying time is less than 5 minutes, the photoresist is etched by the etching solution during the etching process. This is because the pattern is not broken and thus the pattern is not formed, and the photoresist is not smoothly removed in the subsequent photoresist removal step due to excessive curing in excess of 60 minutes.

In addition, the AC power in the step (S4) is a frequency of 5 ~ 60Hz, current density 0.1 ~ 10A / ㎠ range, at the current density of less than 5kHz and more than 10A / ㎠ and excessive etching proceeds to break the pattern This is because the etching proceeds less at the current density of more than 60 mA and more than 0.1 A / cm 2, so that etching to the pattern is not performed smoothly, and the electrolyte in the step S4 is less than 20 g / l Al. It is preferable to use ions, 0.5-5 M hydrochloric acid and 0.01-2 M sulfuric acid. When there are more than 20 g / l Al ions, the interference of Al ions increases, which hinders the progress of etching, and less than 0.5 M hydrochloric acid. Etching does not proceed well at sulfuric acid concentration of less than 0.01M, the etching proceeds excessively at the sulfuric acid concentration of more than 5M hydrochloric acid and more than 2M, the primary etching in the step (S4) is the temperature of the electrolyte solution 10 to 60 seconds at 10 to 60 ° C This is because the etching proceeds poorly at a temperature of less than 10 ° C. and a time of less than 10 seconds, and excessive etching occurs at a temperature exceeding 60 ° C. and a time exceeding 60 seconds.

In addition, the drying in the step (S5) is performed by washing the etched aluminum current collector with distilled water and then removing the residual photoresist with a photoresist remover containing acetone, 2 to 15 minutes at a temperature of 50 ~ 500 ℃, less than 50 ℃ At the temperature of less than 2 minutes and the drying is not well done, the surface of the aluminum hydration reaction proceeds to form an amorphous oxide film, the oxidation surface of the aluminum surface at a temperature of more than 500 ℃ and more than 15 minutes A crystalline oxide film can be formed, as described above.

In addition, the secondary etching in the step (S6) is applied by etching the AC power, the AC power is preferably a frequency of 10 ~ 90kHz, the current density of 0.1 ~ 10A / ㎠ range. This results in excessive etching at breakdown of the pattern at current densities below 10 Hz and above 10 A / cm 2, and less etching at current densities above 90 Hz and below 0.1 A / cm 2. This is because it may not be made smoothly.

In addition, the secondary etching uses an etching solution containing 10 ~ 30g / L Al ions, 100 ~ 300g / L (q) Cl ions, and 5 ~ 30g / L SO ₄ ions, 30g / L in the ionic liquid If there are more Al ions, the interference of Al ions increases, which hinders the progress of etching, and the etching does not proceed with Cl ions less than 100 g / l and SO ₄ ions less than 5 g / l, and Cl ions greater than 300 g / l and This is because etching may proceed excessively in SO ₄ ions of more than 30 g / L, and the secondary etching is preferably performed at 30 to 90 ° C. for 10 to 60 seconds. This is because the etching progresses poorly at a temperature of less than 30 ° C and a time of less than 10 seconds, because excessive etching may be made at a temperature of more than 90 ° C and a time of more than 60 seconds.

In addition, the washing and drying in the step (S7) is performed for 2 to 15 minutes at a temperature of 50 ~ 500 ℃ after washing with distilled water, which is not dried well at a temperature of less than 50 ℃ and less than 2 minutes This is because the aluminum surface undergoes a hydration reaction to form an amorphous oxide film, and at a temperature of more than 500 ° C. and a temperature of more than 15 minutes, the aluminum surface may undergo an oxidation reaction to form a crystalline oxide film.

In addition, the three-dimensional pattern in the present invention is formed using photolithography.

The present invention also provides an aluminum current collector manufactured as described above, and provides an ultracapacitor including the electrode as described above.

According to the present invention, there is provided an etching method for expanding the surface area of an aluminum current collector which can effectively increase the contact area between an aluminum current collector and an active material, and providing a method of manufacturing an ultra-capacitor capacitor that improves an effective capacity by applying the current collector. Has an effect.

1 is a photograph showing an aluminum current collector having a three-dimensional pattern structure formed by photolithography produced by way of an embodiment.
Figure 2a is a photo substitute photo using a photolithography on the surface of the aluminum current collector (Photo resist) to form a pattern of 10㎛ size and the interval between the shapes to form a pattern of 10㎛.
FIG. 2B is a drawing substitute photograph in which a pattern having a size of 50 μm with a photoresist on the surface of an aluminum current collector and a space of the shapes having a thickness of 50 μm using photolithography is formed.
FIG. 2C is a drawing substitute photograph in which a pattern of 100 μm in size and a space of 50 μm in intervals between the shapes are formed on a surface of an aluminum current collector using photolithography.
FIG. 2D is a photographic drawing in which a pattern having a size of 50 μm with a photoresist on the surface of an aluminum current collector and a space between the shapes at 10 μm using photolithography is formed.
Fig. 2 is a drawing substitute photograph which forms a pattern of a portion where the photosensitive liquid remains and a portion that is removed;
Figure 4 is a substitute photograph of the aluminum current collector after selectively etching only the aluminum of the portion where the photoresist is removed.
Fig. 5 is a photograph of the aluminum current collector drawing after etching, after removing all of the photoresist remaining on the surface of the aluminum current collector with a remover.
6 is a configuration diagram of an ultra-capacitor capacitor electrode to which an aluminum current collector manufactured through an embodiment is applied.
FIG. 7 is a diagram illustrating an internal configuration of an ultracapacitor prepared by applying an aluminum current collector manufactured through an embodiment. FIG.
[Description of Major Symbols in Drawing]
10: active material
20: pattern etched aluminum current collector
30: electrolytic cell
40: negative electrode applying pattern etched aluminum current collector
50: positive electrode using a pattern-etched aluminum current collector

In order to practice the present invention, first, the purity of aluminum is 99.00 to 99.99%, and as impurities, the organic material on the surface of the aluminum collector of 10 to 100 μm added with Cu: 4,000 ppm, Si: 2,000 ppm, Fe: 2,000 ppm or less is added. To remove 1) acetone solution 2) methanol solution 3) sequential washing with distilled water and dried with nitrogen.

Then, a photoresist is applied evenly on the surface of the aluminum current collector to a thickness of 0.5 μm to 50 μm, and then the solvent (Solvent) present in the photo resist is evaporated to maintain a solid photoresist film state. Dry for 5 ~ 30 minutes at a temperature of ~ 150 ° C, and shape 10 ~ 500㎛ with chromium on the material that can transmit UV (Ultra Violet) light such as quartz A mask shaped as a combination of μm is positioned on the aluminum current collector to which the photoresist is applied, and then irradiated with UV light to selectively expose the photoresist.

Thereafter, a developer (alkaline solution) is sprayed onto the exposed aluminum current collector to selectively remove only the exposed or unexposed photoresist, and the remaining photoresist is completely hardened for 5 to 60 minutes at a temperature between 50 and 150 ° C. Complete the pattern formation on the whole.

First or later, a primary etching electrolyte is prepared by adding 20 g / l or less of Al ions, 0.5 to 5 M of hydrochloric acid, and 0.01 to 2 M of sulfuric acid.

Then, two carbon plates are used as the counter electrodes, and an aluminum current collector formed with a photoresist is positioned therebetween to apply AC power. The AC power source has a frequency of 5 Hz to 60 Hz and a current density of 0.1 to 10 A /. The aluminum current collector is etched for 10 to 60 seconds at a temperature of the electrolyte solution between 10 and 60 ° C. as cm 2.

The etched aluminum current collector is washed with distilled water, and all remaining photoresist is removed using a remover such as acetone, followed by drying for 2 to 15 minutes at a temperature of 50 to 500 degrees.

First or after Al between 10 and 30 g / l Ions and Cl between 100 and 300 g / l Ions, and SO ₄ between 5 and 30 g / l The secondary etching electrolyte is prepared by adding ions.

Next, AC power is applied with the two carbon plates as the counter electrodes and the first current etched aluminum current collector is positioned therebetween. The frequency of the AC power is 10 kHz to 90 kHz and the current density is 0.1 to 10 A. / Cm2 and secondary etching of the aluminum current collector for 10 to 60 seconds at the electrolyte temperature between 30 ~ 90 ℃, washed with distilled water after the secondary etched aluminum current collector and dried for 2-15 minutes at 50 ~ 500 ℃ temperature The present invention is completed.

Hereinafter, the present invention will be described in detail by way of examples, which are intended to help those of ordinary skill in the art, but the present invention is not limited to the following examples.

Example 1 Fabrication of an aluminum current collector having a three-dimensional pattern structure using a photoresist

An aluminum foil having a purity of 99.90% and a thickness of 0.030 mm was sequentially washed with 1) acetone solution 2) methanol solution 3) distilled water and dried with nitrogen.

Photoresist is applied evenly on the surface of aluminum current collector to a thickness of 0.5㎛, dried for 15 minutes at a temperature of 80 degrees, then masked to form a pattern of 80㎛ diameter and the pattern of the interval of 70㎛ ) Was placed on the aluminum current collector to which the photoresist was applied, and then irradiated with UV light to selectively expose the photoresist.

The developer was sprayed onto the exposed aluminum current collector to selectively remove only the unexposed photoresist, and the remaining photoresist was completely hardened at a temperature of 100 degrees for 15 minutes to complete pattern formation on the aluminum current collector.

After the primary etching electrolyte was prepared by adding 15 g / l Al ion, 1 M hydrochloric acid, and 2 M sulfuric acid, two carbon plates were used as counter electrodes, and an aluminum current collector patterned with photoresist was placed therebetween. Power was applied.

The AC power source is 50 kHz, the current density is 3A / ㎠ and the temperature is 45 ℃, the aluminum current collector is first etched for 50 seconds, and then the etched aluminum current collector is washed with distilled water and the surface of the current collector with acetone. After removing all of the photoresist remaining in the dried at 150 ° C temperature.

10 g / l Al Ion and Cl of 120g / l Ions, and SO _{4 at} 20 g / l After the secondary etching electrolyte was prepared by adding ions, AC power was applied with two carbon plates as the counter electrodes and the aluminum current collector subjected to the primary etching being positioned therebetween.

The frequency of the AC power supply was 30 Hz, the current density was 1 A / cm 2, and secondary etching was performed on the aluminum current collector for 45 seconds at an electrolyte temperature of 45.

The secondary etched aluminum current collector was washed with distilled water and dried at a temperature of 125 degrees for 10 minutes.

An aluminum current collector having a three-dimensional pattern surface structure as described above is shown in FIG. 1.

Example 2 Fabrication of an Ultra-Capacitor Capacitor Applying an Aluminum Current Collector Having a Three-dimensional Pattern Structure

80 g of activated carbon (specific surface area 2,100 m ² / g), 20 g of carbon black, and 4 g of binder were added to the stirring vessel, and after stirring for 30 minutes using a stirrer, 200 g of pure water was added and stirred for 200 minutes. The slurry was prepared by further stirring for a minute.

An electrode was prepared by coating the slurry at 0.6 g / cm 3 on an aluminum current collector having a three-dimensional pattern structure manufactured using a photoresist.

The electrode was first dried at 70 ° C. for 20 minutes and then secondly dried at 100 ° C. for 240 minutes.

Cut the dried electrode to the size of 3.5cm × 4.5cm (15.75㎠) and prepare two sheets, and stack the lead tabs in the order of one electrode prepared above → electrolytic cell → the remaining one sheet of the electrode prepared above. The exterior was covered with an aluminum pouch.

An electrolyte (1M TEABF ₄ / ACN) was put into the pouch, vacuum impregnated, and sealed to prepare an ultracapacitor.

[Comparative Example]

80 g of activated carbon (specific surface area 2,100 m ² / g), 20 g of carbon black, and 4 g of binder were added to the stirring vessel, and after stirring for 30 minutes using a stirrer, 200 g of pure water was added and stirred for 200 minutes. The slurry was prepared by further stirring for a minute.

In general, an electrode was prepared by coating the slurry at 0.6 g / cm 3 on a commercially available aluminum current collector for EDLC.

The electrode was first dried at 70 ° C. for 20 minutes and then secondly dried at 100 ° C. for 240 minutes.

Cut the dried electrode to the size of 3.5cm × 4.5cm (15.75㎠) and prepare two sheets, and stack the lead tabs in the order of one electrode prepared above → electrolytic cell → the remaining one sheet of the electrode prepared above. Take out the exterior with aluminum pouch.

An electrolyte (1M TEABF4 / ACN) was put into the pouch, vacuum impregnated, and sealed to prepare an ultracapacitor.

[Evaluation example]

The ultracapacitors prepared in Examples and Comparative Examples were all charged with a constant current of 15.75 mA and a constant voltage charge of 2.7 V, held for 30 minutes, and then discharged with a constant current (15.75 mA).

The capacity was measured under the above conditions, and the results are shown in Table 1.

division Example Comparative example Capacity (F) 3.56 2.75

As can be seen from the above table, the present invention provides an aluminum current collector that can provide an ultra-capacitor.

Claims (21)

Washing the aluminum foil current collector and then drying with nitrogen (S1);
Applying a photoresist on the surface of the dried aluminum foil current collector and then drying the photoresist to selectively expose the photoresist to be cured (S2);
After the step (S2), spraying the developer on the exposed aluminum current collector to selectively remove the unexposed photoresist and completely curing the remaining photoresist to complete the formation of the pattern on the aluminum current collector (S3);
Placing two carbon plates as opposite electrodes, and placing a patterned aluminum foil current collector between the two carbon plates to apply an AC power source and primary etching the aluminum current collector in the electrolyte (S4);
Drying the etched aluminum current collector (S5);
After the step (S5) and the second carbon plate as a counter electrode and the first etching after the secondary aluminum by placing a dried aluminum current collector between the opposite electrodes (S6); And
A method of manufacturing an aluminum current collector having a three-dimensional pattern structure including the step of washing and drying the secondary etched aluminum foil (S7), wherein the aluminum foil in the step (S1) has a purity of 99.00 to 99.99% and a thickness of 10. Method for producing an aluminum current collector having a three-dimensional pattern structure, characterized in that ~ 100㎛. delete The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the photosensitive liquid coating in the step S2 is performed at a thickness of 0.5 to 50 µm. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the drying in the step (S2) is performed for 5 to 30 minutes at a temperature of 50 to 150 ° C. The method of claim 1, wherein the exposure in the step S2 is performed by selectively irradiating UV light after placing a mask formed by forming a pattern of chromium on a transparent material on an aluminum current collector coated with a photosensitive liquid. A method of manufacturing an aluminum current collector having a pattern structure. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 5, wherein the mask is a UV light transmitting material including quartz. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 5, wherein the mask is a pattern in which a shape having a size of 10 to 500 µm and a shape interval are combined at 10 to 500 µm. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the developer in step S3 is an acid or an alkaline solution excluding neutrality. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the curing in the step S3 is performed for 5 to 60 minutes at a temperature of 50 to 150 ° C. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the AC power in the step S4 has a frequency of 5 to 60 Hz and a current density of 0.1 to 10 A / cm 2. The method of claim 1, wherein the electrolyte in the step (S4) of the aluminum current collector having a three-dimensional pattern structure, characterized in that the Al ion of less than 20g / ℓ, 0.5 ~ 5M hydrochloric acid and 0.01 ~ 2M sulfuric acid Manufacturing method. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the primary etching in the step S4 is performed for 10 to 60 seconds at a temperature of 10 to 60 ° C of the electrolyte solution. The method of claim 1, wherein the drying in the step (S5) is to wash the etched aluminum current collector with distilled water and then remove the residual photoresist with a photoresist remover containing acetone, and is performed for 2 to 15 minutes at a temperature of 50 ~ 500 ℃. A method for producing an aluminum current collector having a three-dimensional pattern structure, characterized in that. The aluminum current collector having a three-dimensional pattern structure according to claim 1, wherein the secondary etching in the step S6 is performed by applying an AC power source having a frequency of 10 to 90 Hz and a current density of 0.1 to 10 A / cm 2. Manufacturing method. delete The three-dimensional etching method according to claim 14, wherein the secondary etching is performed in an etching electrolyte solution containing 10 to 30 g / l Al ions, 100 to 300 g / l Cl ions, and 5 to 30 g / l SO ₄ ions. A method of manufacturing an aluminum current collector having a pattern structure. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 14, wherein the secondary etching is performed for 10 to 60 seconds at 30 to 90 ° C. The method of claim 1, wherein the washing and drying in the step (S7) is a method for producing an aluminum current collector having a three-dimensional pattern structure, characterized in that for 2 to 15 minutes at a temperature of 50 ~ 500 ℃ after washing with distilled water. The method of manufacturing an aluminum current collector having a three-dimensional pattern structure according to claim 5, wherein the three-dimensional pattern is photolithography. delete delete

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