KR20140111724A - Integrated electrodes-bipolar plate and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an integrated electrode-bipolar plate and a method for manufacturing the same. An electrode and a bipolar plate are joined and integrated by a thermostatic adhesive sheet. The thermostatic adhesive sheet contains a certain kind of thermostatic resin and conductive filler, thus enhancing energy efficiency due to contact resistance at interfaces. Moreover, the adhesive sheet is also capable of performing the role as a protective coating surface, such as against acidity, in order to provide an integrated electrode-bipolar plate which can provide excellent durability stability, work stability and continuity of the processes.

Description

[0001] INTEGRATED ELECTRODES-BIPOLAR PLATE AND MANUFACTURING METHOD THEREOF [0002]

The present invention relates to an integrated electrode-bipolar plate with improved energy efficiency and a method of manufacturing the same.

Redox flow battery is one of the core products closely related to the energy revolution, renewable energy, greenhouse gas reduction, rechargeable battery and smart grid, which have recently attracted the greatest attention in the world. Energy storage system (ESS, Energy Storage System) that stores energy.

Among them, the entire vanadium redox flow cell has been developed by Maria Kazacos (1995) of the New South Wales university in Australia, which is rich in vanadium resources, and is now undergoing the demonstration and commercialization stage.

The pre-vanadium based redox flow cell comprises a conductive metal plate as a current collector; A bipolar plate that prevents corrosion of the current collector from strong acid and simultaneously acts as a high-conductivity collector; Carbon felts which are carbon fibers used as electrodes; The electrolytic solution is prepared by stacking basic unit cells composed of V ^{4 +} (anode), V ^{2 +} (cathode) ions and cation exchange membrane according to the oxidized state of vanadium ions and corresponding to a specific capacity.

The performance of the redox flow cell is evaluated by voltage, current and energy efficiency characteristics. The characteristics are the contact resistance between the interface between the carbon fiber and the bipolar plate as the electrode, the multi-sheet contact resistance of the carbon fiber as the electrode, And so on.

Japanese Laid-Open Patent Publication No. 2001-196071 discloses a method in which a carbon fiber-shaped electrode and a bipolar plate are bonded to each other without a separate binding binder. However, this method has a problem that the initial cell resistance is high, and when the bipolar plate is used for a long period of time, the bipolar plate is corroded by strong acid, which makes it difficult to maintain the pressure contact point of the bipolar plate and the electrode continuously. That is, there is a disadvantage in that the energy efficiency characteristic is deteriorated when it is used for a long period of time.

In addition, the carbon fiber-shaped electrode is formed by mixing resin to form a contact point between the bundles of carbon fibers and then subjecting it to hot-pressing. In many cases, the amount of resin used as the binder is uneven and aggregates, And the energy efficiency is lowered.

In order to improve these disadvantages, the steps of mixing, bonding, thermoforming and carbonizing a resin having an average particle diameter of 20 탆 or less and a short fiber have a more uniform phase than that of dispersing the resin in the conventional nonwoven fabric, Can be manufactured with the improved electrode assembly. However, this may cause aggregation due to the resin or damage of the ion exchange membrane due to an increase in density.

In addition, Japanese Laid-Open Patent Application No. 1999-162496 discloses a method of using a plate integrally formed by laminating carbon felt as an electrode to form a laminate, and filling both ends of each laminate with a thermosetting resin. Although the above method can reduce the contact resistance between the electrode plate, the substrate and the electrode plate or reduce the internal resistance of the battery in the planar direction, there is a disadvantage that the resistance can be increased due to uneven filling of the thermosetting resin.

The present invention provides an integrated electrode-bipolar plate capable of reducing the contact resistance due to the bonding of the electrode and the bipolar plate and reducing the occurrence of contact resistance and the like due to non-uniformity during bonding, thereby improving energy efficiency .

In addition, the present invention has an advantage in that the integrated electrode-bipolar plate can maintain the operation stability and continuity of the process.

In order to achieve the above object, the present invention provides an integrated electrode-bipolar plate, wherein the electrode and the bipolar plate are joined together by a thermosetting adhesive sheet, and the thermosetting adhesive sheet contains a thermosetting resin and a conductive filler. provides

 The thermosetting adhesive sheet may be contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the thermosetting resin.

The thermosetting adhesive sheet may have a thickness of 1 to 500 mu m.

The thermosetting resin may be at least one selected from the group consisting of a polyester resin, a urea resin, an amino resin, a polyurethane resin, an alkyd resin, a furan resin, a melamine resin, an epoxy resin and a phenol resin.

The conductive filler has a particle size of 10 nm to 900 탆 and may be at least one selected from the group consisting of natural graphite, artificial graphite, carbon fiber and carbon nanofiber.

The present invention also relates to a method for manufacturing an integrated circuit comprising a step of inserting a thermosetting resin and a thermosetting adhesive sheet containing a conductive filler between an electrode and a bipolar plate to produce a laminate, A bipolar plate having an electrode-bipolar plate.

The laminate can be manufactured by bonding a thermosetting adhesive sheet to one surface of an electrode under low-temperature pressurizing conditions, and then bonding a bipolar plate to the thermosetting adhesive sheet.

The low-temperature pressurization can be carried out at a temperature of room temperature to 60 ° C and a pressure of 0.1 to 1 MPa.

The laminate can be produced by applying a composition for forming a thermosetting adhesive sheet on one surface of a bipolar plate and drying the thermosetting adhesive sheet to produce a thermosetting adhesive sheet to which a bipolar plate is bonded, and then bonding electrodes on the thermosetting adhesive sheet .

The thermosetting resin may be at least one selected from the group consisting of a polyester resin, a urea resin, an amino resin, a polyurethane resin, an alkyd resin, a furan resin, a melamine resin, an epoxy resin and a phenol resin.

The conductive filler has a particle size of 10 nm to 900 탆 and may be at least one selected from the group consisting of natural graphite, artificial graphite, carbon fiber and carbon nanofiber.

The pressure-hardening can be carried out at a temperature of 60 to 180 DEG C and a pressure of 1 to 10 MPa for 0.3 to 5 hours.

The pressure-hardening may be performed so that the electrode thickness after curing is 0.3 to 0.5 with respect to the electrode thickness before curing.

The electrode may be thermally oxidized at 500 to 600 占 폚 for 3 to 12 hours.

The thermosetting adhesive sheet may be contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the thermosetting resin.

The thermosetting adhesive sheet may have a thickness of 1 to 500 mu m.

The integrated electrode-bipolar plate according to the present invention is advantageous in that the electrode and the bipolar plate are bonded by the adhesive sheet, and problems such as lowering of energy efficiency such as contact resistance of the conventional junction interface can be improved.

In addition, the integrated electrode-bipolar plate according to the present invention has an advantage that the adhesive sheet serves as an acid-resistant protective coating surface, and durability stability of the electrode and the bipolar plate can be secured.

In addition, the integrated electrode-bipolar plate according to the present invention can uniformly disperse the conductive filler in the adhesive sheet, easily adjust the thickness of the sheet, and cure the composition for forming an adhesive sheet at low temperature, There is an advantage that the continuity of the process can be maintained.

1 is a cross-sectional view (a) of an integrated electrode-bipolar plate according to the present invention and a cross-sectional view (b) of a basic unit cell using the same.
FIG. 2 is a SEM photograph of a joint surface of an integrated electrode-bipolar plate according to the present invention,
3 is a graph showing the results of charge / discharge tests using the electrode-bipolar plate of Example 1 and the electrode and bipolar plate of Comparative Example 1. Fig.

The present invention relates to an integrated electrode-bipolar plate with improved energy efficiency and a method of manufacturing the same.

Hereinafter, the present invention will be described in detail.

1 (a), the electrode 1 and the bipolar plate 2 of the integrated electrode-bipolar plate of the present invention are joined together by the thermosetting adhesive sheet 4 and integrated.

The thermosetting adhesive sheet is formed using a composition for producing a thermosetting adhesive sheet containing a thermosetting resin and a conductive filler.

The thermosetting resin may be at least one selected from the group consisting of a polyester resin, a urea resin, an amino resin, a polyurethane resin, an alkyd resin, a furan resin, a melamine resin, an epoxy resin and a phenol resin, It is preferable to have a hydrophobic molecular structure for compatibility with a low-foaming curing resin, a low-temperature curing resin or a bipolar plate surface.

The conductive filler may be at least one selected from the group consisting of artificial graphite, activated carbon, natural graphite, carbon black, carbon fiber, carbon nanotube, and graphene. Considering the production of a highly conductive adhesive sheet, it is preferable that the conductive sheet has a high electrical conductivity or a high dispersibility in the resin.

The conductive filler preferably has a particle size of 10 nm to 900 占 퐉, preferably 10 nm to 300 占 퐉, more preferably 1 to 100 占 퐉 in consideration of compatibility with a thermosetting resin and dispersibility. If the particle size is less than 10 nm, the filling volume increases with a low density to make it difficult to disperse. When the particle size exceeds 900 탆, aggregation problems after dispersion may occur.

The thermosetting adhesive sheet preferably contains 1 to 50 parts by weight, preferably 5 to 50 parts by weight, of the conductive filler per 100 parts by weight of the thermosetting resin. If the content is less than 1 part by weight, the amount of resin after the production of the conductive adhesive sheet may be excessively present, resulting in an increase in electrical resistance and energy efficiency. If the content is more than 50 parts by weight, A void formation problem may occur in the interface junction of the electrode.

The composition for preparing a thermosetting adhesive sheet according to the present invention may further contain an organic solvent, a curing agent and the like in consideration of curability, ease of sheet production, and viscosity control.

In addition, the thermosetting adhesive sheet may further contain an additive such as a noble metal filler, a curing agent, a dispersing agent, and a solvent within a range not deviating from the object of the present invention.

The content of the organic solvent, the curing agent, the additive and the like can be appropriately controlled within a range in which the adhesive sheet of the present invention can perform the role. Specifically, the organic solvent preferably contains 100 to 200 parts by weight based on 100 parts by weight of the thermosetting resin, and the noble metal filler, curing agent and additives are preferably contained in an amount of less than 5 parts by weight based on 100 parts by weight of the thermosetting resin .

The integrated electrode-bipolar plate according to the present invention is manufactured by inserting a thermosetting resin and a thermosetting adhesive sheet containing a conductive filler between an electrode and a bipolar plate to produce a laminate and hot-curing the laminate.

At this time, the thermosetting resin and the conductive filler are the same as those described above.

The laminate of the present invention can be produced by bonding a thermosetting adhesive sheet to one surface of an electrode under low temperature pressurization, and then bonding a bipolar plate to the thermosetting adhesive sheet.

The production of the thermosetting adhesive sheet is carried out using an apparatus for producing an adhesive sheet such as a micrometer film applicator or the like. The adhesive sheet produced by using the apparatus performs defoaming because microbubbles are generated. The degassing is preferably a low-temperature defoaming process for drying at 30 to 60 DEG C for 10 to 30 minutes.

If the thickness of the heat-cured adhesive sheet is less than 1 탆, it may be difficult to maintain the bipolar plate-electrode interfacial bonding layer. If the thickness exceeds 500 탆, the bipolar plate The interfacial resistance between the electrodes increases and the energy efficiency may decrease.

It is preferable that the bonding electrode and the surface of the bipolar plate perform a cleaning operation. In particular, the electrode is preferably subjected to surface oxidation, which is generally the most stable process, It is advisable to perform for 12 hours.

If the thermal oxidation temperature is less than 500 ° C, it may take several days to form functional groups on the electrode surface or may be difficult to optimize the activation. When the temperature exceeds 600 ° C, the electrode material is thermally oxidized by ashing, You can lose.

Thereafter, the prepared thermosetting adhesive sheet is bonded to the thermally oxidized electrode surface on the low temperature-pressurized condition to produce a thermosetting adhesive sheet to which the electrodes are bonded. The low temperature pressurization is preferably carried out at a temperature of from room temperature to 60 DEG C and a pressure of from 0.1 to 1 MPa. Since the thermosetting resin constituting the thermosetting adhesive sheet of the present invention can be cured at a low temperature, bonding can be performed when a certain amount of pressure is applied.

A bipolar plate is bonded to the thermosetting adhesive sheet to which the electrode is bonded to produce a laminate.

The laminate of the present invention is obtained by applying a composition for forming a thermosetting adhesive sheet on one surface of a bipolar plate and drying the thermosetting adhesive sheet to produce a thermosetting adhesive sheet to which a bipolar plate is bonded, Can be manufactured.

The above coating and drying are generally used in the art and are not particularly limited, and drying is preferably performed until the solvent of the composition for forming a thermosetting adhesive sheet volatilizes to form a sheet. The drying conditions can be appropriately selected depending on the type of the solvent to be volatilized.

Thereafter, the laminate is thermocompression-cured to produce an integrated electrode-bipolar plate.

The thermosetting is preferably performed at a temperature of 60 to 180 ° C and a pressure of 1 to 10 MPa for 0.3 to 5 hours. If the hot-curing temperature is less than 60 ° C, the curing time is delayed for a long time. Uncalated materials may remain as an interfacial resistance. If the temperature exceeds 180 ° C, resistance to gas generation and pores of the structure may occur.

At this time, it is preferable that the pressure-hardening is performed by applying a load to the electrode thickness 1 before curing to 0.3 to 0.5 of the electrode thickness after curing. If the thickness of the electrode after curing is less than 0.3, the bonding force of the interface between the bipolar plate and the electrode can be deteriorated. If the thickness is more than 0.5, the electrode may be damaged.

It is also possible to provide a pre-vanadium based redox flow cell comprising an integrated electrode-bipolar plate (FIG. 1 (a)) according to the present invention. The entire vanadium-based redox flow cell is provided with a basic unit cell (FIG. 1 (b)) including an integrated electrode-bipolar plate, and the other configurations are not limited to those generally used in the art . Such a configuration can be easily implemented by those skilled in the art, and a description thereof will be omitted.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example 1

1) Thermosetting adhesive composition

20 parts by weight of toluene (Samseon Chemical Co., Ltd.) as an organic solvent was mixed with 90 parts by weight of a polyester resin (Liza Ad 2300, product of Calix chem), and 20 parts by weight of artificial graphite (synthetic-graphite, Asbury) as a conductive filler 10 parts by weight, and the mixture was stirred at 1000 rpm for 6 hours to prepare a thermoset adhesive composition.

2) Thermosetting adhesive sheet

Using the micrometer film applicator, the thermosetting adhesive composition prepared in 1) above was made into a thermosetting adhesive sheet having a thickness of 125 탆. The adhesive sheet was subjected to a low temperature defoaming process of drying at 30 to 60 ° C for 10 to 30 minutes to remove minute bubbles.

3) Integrated electrode-bipolar plate

The surface of the bipolar plate (SK507 product, Morgan Korea) was cleaned and the electrode carbon felt (WDF product, Morgan AM & T) was thermally oxidized at 550 ° C for 5 hours.

The thermosetting adhesive sheet prepared in 2) was cut to fit the size of the electrode, and was bonded to one surface of the electrode at low temperature. At this time, the low-temperature bonding was carried out at a temperature of 60 DEG C and a pressure of 0.5 MPa.

Thereafter, a bipolar plate was bonded on the thermosetting adhesive sheet to which the electrode was bonded, and then thermocompression-cured to produce the integrated electrode-bipolar plate of Fig. 1. At this time, the thermocompression hardening was performed at a temperature of 155 캜 and a pressure of 7 MPa, and the thickness before hot-pressing was 125 탆 and the thickness after hot-pressing was 80 탆.

2 is a SEM photograph of the interface between the electrode and the bipolar plate.

Example 2

Except that 20 parts by weight of toluene (SEMON CHEMICAL CO., LTD.) As an organic solvent was mixed with 70 parts by weight of a polyester resin (Liza Ad 2300, product of Calix chem Co., Ltd.) Mu] m, synthetic-graphite, Asbury) was used to prepare an integrated electrode-bipolar plate.

Example  3

Except that 20 weight parts of toluene (Samseon Chemical Co., Ltd.) as an organic solvent was mixed with 50 weight parts of a polyester resin (Liza Ad2300, product of Calix chem) and 100 weight parts of artificial graphite (particle size 2 Mu] m, synthetic-graphite, Asbury) was used to prepare an integrated electrode-bipolar plate.

Example  4

90 parts by weight of a polyester resin (product of Liza Ad 2300, Calix chem) was mixed with 50 parts by weight of toluene (Samseon Chemical Co., Ltd.) as an organic solvent, and natural graphite (particle size 25 Mu] m, graphite, Brazil Graphite) was used to prepare an integrated electrode-bipolar plate.

Example  5

Except that 90 parts by weight of a polyester resin (product of Liza Ad 2300, Calix chem) and 50 parts by weight of toluene (Organic Chemistry) were mixed as the organic solvent, and carbon nanotubes having a diameter of 150 nm , Length 6 μm, carbon nano-tube, VGCF-H product, Showa Denko) were used to prepare an integrated electrode-bipolar plate.

Example  6

60 parts by weight of a curing agent (HN2200, manufactured by Kukdo Chemical Co., Ltd.) was mixed with 90 parts by weight of an epoxy resin (product YD127, manufactured by Kukdo Chemical Co., Ltd.) -graphite, Asbury) and an accelerator (BDMA product, Kukdo Chemical Co., Ltd.) were used to fabricate an electrode-bipolar plate integrated with each other.

Example  7

(KC6301, Kangnam Chemical Co., Ltd.) was mixed with 50 parts by weight of methanol as an organic solvent (manufactured by Seonjeon Chemical Co., Ltd.), and 100 parts by weight of artificial graphite (particle size 2 탆, synthetic-graphite, Asbury) was used to prepare an integrated electrode-bipolar plate. At this time, the thermosetting adhesive sheet was made to have a thickness of 250 mu m.

Comparative Example  One

The electrode and the bipolar plate of Example 1 were used without bonding each other.

Test Example

Unit cells were fabricated using the integrated electrode-bipolar plates of the above examples and their electrical and chemical properties were evaluated.

Specifically, a pair of end plates; A pair of current collectors (5) formed inside the end plate; A unit cell including a pair of integrated electrode-bipolar plates formed inside the current collector and a cation exchange membrane 6 between the integrated electrode-bipolar plates was fabricated (FIG. 1).

The electrochemical characteristics (current density, resistance, current efficiency, voltage efficiency, and energy) of the unit cell and the electrolyte solution of the 2 M sulfuric acid (Duksan Chemical Company) / vanadium (Aldrich, 97%) solution were measured by using Nafion 117 product Efficiency) was evaluated.

At this time, the current density is 40 mA / cm 2, and the applied voltage range is 0.6 to 1.6 V.

The resistor was charged and discharged at a constant current of 40 mA / cm 2 under a charge cut-off voltage of 1.6 V and a discharge cut-off voltage of 0.8 V, and the resistance against the potential difference of the voltage was measured by cutting off the current for 5 seconds at the open circuit voltage of 1.6 V. The current efficiency (%) was calculated using discharge capacity / charge capacity 100, voltage efficiency (%) using discharge voltage / charging voltage 100, and energy efficiency (%) using current efficiency voltage efficiency / 100.

In Comparative Example 1, a unit cell was manufactured using an electrode and a bipolar plate, respectively, and electrical and chemical properties were evaluated using the unit cell.

division Current density
(MA / cm2) resistance
(Ω) Current efficiency
(%) Voltage efficiency
(%) Energy efficiency
(%) Example 1 40 0.12 88.6 92.2 81.7 Example 2 40 0.14 87.2 92.1 80.3 Example 3 40 0.20 86.3 90.5 78.1 Example 4 40 0.15 84.6 92.2 78.0 Example 5 40 0.25 86.5 90.2 77.7 Example 6 40 0.19 87.0 90.6 78.8 Example 7 40 0.20 85.4 90.1 76.9 Comparative Example 1 40 0.27 81.4 89.3 72.7

3 shows the results of charging / discharging tests using the electrode-bipolar plate of Examples 1 and 2 and the electrode and bipolar plate of Comparative Example 1. Fig. As a result, in Examples 1 and 2, the time taken to reach the maximum voltage was remarkably reduced as compared with Comparative Example 1, and it was also confirmed that the overall efficiency of the unit cell was lower and the energy efficiency due to the increase in voltage and current efficiency was more stable.

1: Electrode
2: bipolar plate
3: Thermosetting adhesive sheet
4: Entire house
6: ion exchange membrane
6: Support plate for cell fixation
7: Pin for fixing the cell

Claims (16)

The electrode and the bipolar plate are joined and integrated by the thermosetting adhesive sheet,
Wherein the thermosetting adhesive sheet contains a thermosetting resin and a conductive filler.
The integrated electrode-bipolar plate according to claim 1, wherein the thermosetting adhesive sheet contains 1 to 50 parts by weight per 100 parts by weight of the thermosetting resin.
The integrated electrode-bipolar plate according to claim 2, wherein the thermosetting adhesive sheet has a thickness of 1 to 500 μm.
The thermosetting resin according to claim 1, wherein the thermosetting resin is at least one selected from the group consisting of a polyester resin, a urea resin, an amino resin, a polyurethane resin, an alkyd resin, a furan resin, a melamine resin, an epoxy resin, Electrode - bipolar plate.
The conductive filler according to claim 1, wherein the conductive filler has a particle size of 10 nm to 900 μm and is at least one selected from the group consisting of artificial graphite, activated carbon, natural graphite, carbon black, carbon fiber, carbon nanotube and graphene Lt; RTI ID = 0.0 > electrode-bipolar plate. ≪ / RTI >
Inserting a thermosetting resin and a thermosetting adhesive sheet containing a conductive filler between the electrode and the bipolar plate to produce a laminate; and
And thermocompression-curing the laminate. ≪ RTI ID = 0.0 > 11. < / RTI >
The integrated electrode-bipolar plate according to claim 6, wherein the laminate is manufactured by bonding a thermosetting adhesive sheet to one surface of an electrode under low-temperature pressing conditions, and then bonding a bipolar plate to the thermosetting adhesive sheet. ≪ / RTI >
[8] The method of claim 7, wherein the low-temperature pressing is performed at a temperature ranging from room temperature to 60 [deg.] C and a pressure of 0.1 to 1 MPa.
7. The bipolar plate according to claim 6, wherein the laminate is formed by applying a composition for forming a thermosetting adhesive sheet on one surface of a bipolar plate and drying the thermosetting adhesive sheet to produce a thermosetting adhesive sheet having a bipolar plate bonded thereto, Wherein the electrode-bipolar plate is fabricated by the method of manufacturing the electrode-bipolar plate.
7. The thermosetting resin composition according to claim 6, wherein the thermosetting resin is at least one selected from the group consisting of a polyester resin, a urea resin, an amino resin, a polyurethane resin, an alkyd resin, a furan resin, a melamine resin, an epoxy resin, (Bipolar plate).
The conductive filler according to claim 6, wherein the conductive filler has a particle size of 10 nm to 900 탆 and is at least one selected from the group consisting of artificial graphite, activated carbon, natural graphite, carbon black, carbon fiber, carbon nanotube, Wherein the bipolar plate has a thickness of less than about 1 mm.
[6] The method of claim 6, wherein the thermocompression is performed at a temperature of 60 to 180 DEG C and a pressure of 1 to 10 MPa for 0.3 to 5 hours.
[12] The method of claim 12, wherein the thermocompression is performed so that the thickness of the electrode after curing is 0.3 to 0.5 after the curing.
[7] The method of claim 6, wherein the electrode is thermally oxidized at 500 to 600 [deg.] C for 3 to 12 hours.
7. The method for manufacturing an integrated electrode-bipolar plate according to claim 6, wherein the thermosetting adhesive sheet contains 1 to 50 parts by weight per 100 parts by weight of the thermosetting resin.
[7] The method of claim 6, wherein the thermosetting adhesive sheet has a thickness of 1 to 500 [mu] m.

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