KR20230131078A - PEMFC bipolar plate test piece for testing efficiency of the fuel cell - Google Patents

Abstract

The present invention relates to a PEMFC separator plate specimen for fuel cell performance testing. More specifically, it relates to a PEMFC separator plate specimen that is 3D printed with resin in the form of a separator plate and then plated with copper to produce a conductive specimen to test fuel cell performance in advance. This relates to PEMFC separator specimens for fuel cell performance testing.

Description

PEMFC bipolar plate test piece for testing efficiency of the fuel cell}

The present invention relates to a PEMFC separator plate specimen for fuel cell performance testing. More specifically, it relates to a PEMFC separator plate specimen that is 3D printed with resin in the form of a separator plate and then plated with copper to produce a conductive specimen to test fuel cell performance in advance. This relates to PEMFC separator specimens for fuel cell performance testing.

Fuel cells, an eco-friendly power generation device, are receiving a lot of attention as a next-generation energy source due to the depletion of fossil resources such as coal and crude oil and global warming caused by carbon dioxide emissions, and research on them is also being actively conducted. In particular, polymer electrolyte membrane fuel cells (PEMFC) are widely used in unmanned aerial vehicles (Drones) and automobiles. Most fuel cells use hydrogen and oxygen, with hydrogen passing through the anode and oxygen passing through the air electrode. Fuel cells have the advantage of being more energy efficient than general combustion engines, emitting no pollutants, and being able to be designed in various sizes and capacities.

Generally, a fuel cell includes a membrane-electrode assembly (MEA) and a separator (or separator, bipolar plate). The membrane-electrode assembly includes a central separator, a catalyst layer formed on both sides of the separator, and a gas diffusion layer formed on the catalyst layer. The separator has the function of uniformly supplying gases (hydrogen and oxygen) to the membrane-electrode assembly, and for this purpose, a channel through which gases (hydrogen and oxygen) pass is formed on one side of the separator.

Specifically, a fuel cell includes a membrane-electrode assembly and separators installed on both sides of the membrane-electrode assembly, which is called a unit cell. These unit cells form a fuel cell stack by stacking tens to hundreds of them in the case of household devices and hundreds or more in the case of automobiles.

Here, the separator plate serves as a passage through which current flows, so it must have a low surface resistance value. Since it functions as a supply passage for reactive gas (hydrogen, oxygen, or air) and an discharge passage for water, it is possible to easily create various passages. Should be. In addition, air permeability must be low to prevent mixing of each gas, and it must have smooth heat management and excellent corrosion resistance. In addition, in order to use fuel cells in limited or small spaces (e.g. automobiles, mobile devices, etc.), the separators used in hundreds to thousands of plates in one stack must be thin yet have high strength.

Existing commercialized graphite separators have high corrosion resistance and good electrical conductivity, but are vulnerable to mechanical shock and vibration and must be maintained at a certain thickness, resulting in high costs.

Additionally, the flow path of a conventional separator plate can be formed in various ways. Specifically, end mill processing is performed by moving the end mill according to the shape of the flow path, so it is a mechanical cutting method using a machining tool and has poor productivity and efficiency. Oil spray processing is completed by forming a mask after dry film coating, exposing it, removing the pattern through dry etching (sandblasting, shot peening, ultrasonic etching, etc.), and then cleaning it. The process steps are complicated, so production efficiency is low. Stepping processing is a processing method that uses a stamper, and although it has high production efficiency, it is impossible to commercialize due to the occurrence of adhesion between the stamping mold and the resin. Lastly, there is a separator plate molding technology using flow-processed molds, which can increase efficiency, but it is difficult to secure product uniformity, mold costs are high, and mold damage is frequent, resulting in high costs.

Accordingly, when testing the performance of a fuel cell for a new flow path, a technology that can economically test separator plates and unit cells is needed instead of expensive graphite separator plates.

As a prior art, Korean Patent Publication No. 10-0432523 “Grid-type bipolar plate for measuring fuel cell performance and method of manufacturing the same” is described.

Therefore, the present invention was proposed to improve such conventional problems, by 3D printing resin in the form of a separator plate and then plating it with copper to produce a conductive specimen to test fuel cell performance in advance. The purpose is to provide PEMFC separator specimens for battery performance testing.

The PEMFC separator plate specimen for fuel cell performance testing according to one aspect of the present invention includes a separator plate molded body printed with resin in the form of a separator plate using a 3D printer; A concave portion formed by applying acetone to the surface of the separator molded body; A copper plating step of applying a conductive adhesive to the separator molded body in which the concave portion is formed and plating copper metal on the adhesive portion formed by polishing the surface so that the conductive adhesive remains only in the concave portion and the separator molded body on which the adhesive portion is formed. It includes a copper plating layer formed through, and the resin is a composite containing 1 to 5 parts by weight of carbon nanomaterial consisting of one or more of carbon nanotubes, graphene, and carbon nanofibers, based on 100 parts by weight of ABS (Acrylonitrile Butadien Styrene). material, the copper plating layer has a thickness of 20 to 80㎛, the separator molded body that has completed the copper plating step has a thickness of 0.7 to 1.7mm, and the adhesive part is formed by buffing the surface of the separator molded body with an abrasive cloth. It is formed by polishing, and in the copper plating step, electroplating is performed using copper salt and a copper electrode plate, and the thickness of the copper plating layer is adjusted according to the resistance value.

Meanwhile, the copper salt may be selected from among copper sulfate, copper chloride, copper oxide, copper methanesulfonate, and copper pyrophosphate.

PEMFC separator specimens for fuel cell performance testing according to an embodiment of the present invention can identify problems in advance before manufacturing a graphite separator.

Additionally, it is cheaper than testing a graphite separator, which can result in economic benefits.

In addition, economic feasibility can be improved when studying the structural shape of electrically conductive components other than graphite separators.

Additionally, the versatility of the test equipment can be increased by manufacturing a conductive structure for connection with standardized unit cell test equipment.

In addition, the effects according to the embodiments of the present invention mentioned above are not limited to the contents described, and may further include all effects predictable from the specification and drawings.

1 is a flowchart of a method for manufacturing a PEMFC separator plate and unit cell specimen for fuel cell performance testing according to an embodiment of the present invention.
2 to 6 are cross-sectional views sequentially showing a method of manufacturing a PEMFC separator and unit cell specimen for fuel cell performance testing according to an embodiment of the present invention.

Hereinafter, the description of the present invention with reference to the drawings is not limited to specific embodiments, and various changes may be made and various embodiments may be possible. In addition, the content described below should be understood to include all conversions, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In the following description, the terms first, second, etc. are terms used to describe various components, and their meaning is not limited, and is used only for the purpose of distinguishing one component from other components.

Like reference numerals used throughout this specification refer to like elements.

As used herein, singular expressions include plural expressions, unless the context clearly dictates otherwise. In addition, terms such as “comprise,” “provide,” or “have” used below are intended to designate the presence of features, numbers, steps, operations, components, parts, or a combination thereof described in the specification. It should be construed and understood as not excluding in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying FIGS. 1 to 6.

In addition, in the following description, unless otherwise specified, the direction facing the front with respect to Figure 1 is referred to as 'front', and the opposite direction is referred to as 'rear'. Accordingly, terms indicating directions such as 'left', 'right', 'upward' and 'downward' are defined as indicating respective directions based on the front and rear.

Figure 1 is a flow chart of a PEMFC separator for fuel cell performance testing and a method of manufacturing a unit cell specimen according to an embodiment of the present invention, and Figures 2 to 6 are a PEMFC separator and unit cell specimen for fuel cell performance testing according to an embodiment of the present invention. This is a cross-sectional view sequentially showing the unit cell specimen manufacturing method.

Referring to Figures 1 and 2, the method of manufacturing a PEMFC separator plate and unit cell specimen for fuel cell performance testing according to an embodiment of the present invention includes a separator plate forming step (S1), a concave forming step (S2), and an adhesive application step. (S3), a polishing step (S4), and a copper plating step (S5).

In the separator plate molding step (S1), the separator plate molded body 10 can be manufactured by printing the resin in the form of a separator plate using a 3D printer. In the separator plate forming step (S1), the separator plate molded body 10 is manufactured using a 3D printer, so a fine flow path can be formed. The method of forming a flow path using a conventional mold has the disadvantage of low reproducibility and that it is difficult to form a fine flow path.

Here, the resin may be ABS (Acrylonitrile Butadien Styrene). However, without being limited thereto, any thermoplastic resin capable of manufacturing the separator plate molded body 10 with a 3D printer device can be used in the technical field of the present invention.

Here, ABS (Acrylonitrile Butadien Styrene) is an amorphous styrene-based thermoplastic resin that has excellent heat resistance, impact resistance, processability, rigidity, and fluidity, as well as excellent overall properties such as dimensional stability, molding processability, and chemical resistance. Initially, ABS was mostly a blend of NBR and AS resin, but recently, graft polymerization of polybutadiene with styrene and acrylic monomers has been widely used.

In addition, the resin may be a composite material containing carbon nanomaterials to improve the mechanical properties of the separator molded body 10. In general, resins used for 3D printers have the disadvantage of low tensile strength, so their strength needs to be improved in order to apply them to separator specimens. Specifically, specimens used to evaluate fuel cell performance can be evaluated multiple times, and after evaluation, specimens can be stored and reevaluated to evaluate stability. At this time, it is important that the shape of the separator plate, including the flow path formed in the separator plate, is maintained.

To solve this problem, the resin used in the present invention may contain carbon nanomaterials. The resin may contain 1 to 5 parts by weight of carbon nanomaterial based on 100 parts by weight of ABS (Acrylonitrile Butadien Styrene). Most preferably, it may contain 3 to 4 parts by weight of carbon nanomaterial based on 100 parts by weight of ABS.

Here, the carbon nanomaterial may be composed of one or more of carbon nanotubes, graphene, and carbon nanofibers. In addition, if the content of carbon nanomaterials is less than 1 part by weight, the effect of improving mechanical properties by carbon nanomaterials may be minimal, and if it exceeds 5 parts by weight, agglomerated areas of carbon nanomaterials may occur and mechanical properties may deteriorate. there is.

In the concave forming step (S2), the concave part 20 may be formed by applying acetone to the surface of the separator plate molded body 10. In the concave forming step (S2), random concave parts 20 can be created on the surface of the separator plate molded body 10, as shown in FIG. 3, by using the property of ABS to dissolve in acetone.

The concave forming step (S2) includes spraying, electrostatic spray, screen printing, brushing, slot die casting, inkjet printing, and injection ( It may include either pouring or dripping. However, it is not limited to this.

Referring to FIG. 4, in the adhesive application step (S3), a conductive adhesive (A) may be applied to the separator plate molded body 10 in which the concave portion 20 is formed. Here, the conductive adhesive (A) can be any conventional adhesive used before resin plating in the technical field of the present invention.

In the adhesive application step (S3), carbon nanomaterials may be mixed with the conductive adhesive (A) to improve adhesion with the copper plating layer 40 to be created in a later process. Here, the carbon nanomaterial may include one or more of carbon nanotubes, graphene, and carbon nanofibers.

Specifically, the adhesive application step (S3) can be performed by mixing 0.5 to 4 parts by weight of carbon nanomaterial with 100 parts by weight of the conductive adhesive (A). At this time, if the amount of carbon nanomaterial in the conductive adhesive (A) is less than 0.5 parts by weight, the effect of improving plating adhesion may be minimal, and if it exceeds 4 parts by weight, the consumption of carbon nanomaterial is greater than the plating adhesion effect and carbon Nanomaterials may clump together, making application difficult. Most preferably, the content of carbon nanomaterials may be 1.5 to 3 parts by weight.

Referring to FIG. 5, the polishing step (S4) may polish the surface of the separator molded body 10 on which the conductive adhesive (A) is applied so that the conductive adhesive (A) remains only in the concave portion 20. In the polishing step (S4), any polishing method commonly used in the technical field of the present invention can be applied.

Specifically, in the polishing step (S4), the surface of the separator plate molded body 10 may be polished by buffing with a polishing cloth. Accordingly, in the polishing step (S4), the conductive adhesive (A) remains only inside the concave portion (20), thereby forming the adhesive portion (30).

Referring to FIG. 6, the copper plating step (S5) may form a copper plating layer 40 by plating copper metal on the surface of the separator plate molded body 10 that has undergone the polishing step (S4).

In the copper plating step (S5), electroplating is performed using copper salt and a copper electrode plate, and the thickness of the copper plating layer can be adjusted depending on the resistance value.

Here, electroplating refers to covering the surface of an object with a thin film of another metal using the principle of electrolysis, and is carried out by connecting direct current electricity between the anode and cathode contained in the plating solution. At this time, the cathode is the object to be plated (base material), and the plating solution uses a solution containing the metal to be coated (electrodeposition metal) as ions. Silver, gold, copper, and nickel, which are stable materials with a small ionization tendency and low reactivity, are metals mainly used in electroplating.

The copper salt used in the plating solution may be selected from copper sulfate, copper chloride, copper oxide, copper methanesulfonate, and copper pyrophosphate. The plating solution may further include a conductive salt, a complexing agent, an antioxidant, a stabilizer, and a brightener. However, without being limited to this, all additives used as plating solutions in the technical field of the present invention can be used.

Additionally, the copper plating layer may have a thickness of 20 to 80 μm. At this time, if the thickness is less than 20㎛, the conductivity effect is minimal and it may be difficult to evaluate fuel cell performance, and if it is more than 80㎛, only the amount of copper used for copper plating increases, which may increase the cost of manufacturing the specimen.

The separator plate molded body 10 that has completed the copper plating step (S5) may have a thickness of 0.7 to 1.7 mm. Most preferably, it may have a thickness of 1.0 to 1.2 mm.

At this time, if the thickness of the separator plate molded body 10 is less than 0.7 mm, the strength may be weakened, and if the thickness is more than 1.7 mm, it may not be desirable for thinning.

In addition, the manufacturing method of the present invention can provide PEMFC separator plates and unit cell specimens for fuel cell performance testing. The PEMFC separator plate and unit cell specimen for fuel cell performance testing of the present invention exhibit similar fuel cell performance to specimens made of conventional graphite, so they can replace conventional specimens.

Accordingly, problems can be identified in advance before manufacturing the PEMFC separator and unit cell specimen graphite separator for fuel cell performance testing of the present invention.

Additionally, it is cheaper than testing a graphite separator, which can result in economic benefits.

In addition, economic feasibility can be improved when studying the structural shape of electrically conductive components other than graphite separators.

Additionally, the versatility of the test equipment can be increased by manufacturing a conductive structure for connection with standardized unit cell test equipment.

Hereinafter, the present invention will be described in more detail through examples, but these are merely for illustrating preferred embodiments of the present invention, and the examples do not limit the scope of the present invention.

[Example]

[Example 1]

After mixing 4 parts by weight of carbon nanofibers with 100 parts by weight of ABS pellets, a resin was manufactured using an extruder. A separator molded body was manufactured using the above resin and an FDM 3D printer.

[Example 2]

After mixing 4 parts by weight of carbon nanofibers with 100 parts by weight of ABS pellets, a resin was manufactured using an extruder. A separator molded body was manufactured using the above resin using a fused deposition modeling (FDM) 3D printer. Random concavities were created on the surface of the manufactured separator molded body using spray. Next, a conductive adhesive was applied and the surface of the separator molded body excluding the concave portion was polished by buffing with a polishing cloth. Finally, copper sulfate and a copper electrode plate were used, a direct current density of 20 mA/cm2 was applied between the anode and the cathode, and copper electroplating was performed until the thickness reached 50 to 60㎛ to prepare a separator specimen of 1.0 to 1.2 mm. did.

[Example 3]

A separator specimen was prepared in the same manner as in Example 2, except that 2 parts by weight of carbon nanotubes were mixed and applied to 100 parts by weight of the conductive adhesive.

[Comparative Example 1]

A separator molded body was manufactured using ABS pellets and an FDM 3D printer.

[Comparative Example 2]

PEMFC separator specimens were manufactured using graphite in a conventional manner.

[Experimental Example 1] Evaluation of mechanical properties

In order to evaluate the mechanical properties of the separator molded body manufactured in Example 1 and Comparative Example 2, the mechanical properties of the separated plate molded body were evaluated. Ten specimens, five at a time, were made to evaluate tensile strength and elastic modulus, and the results are shown in Table 1 below.

Example 1 Comparative Example 1 Tensile strength (MPa) 60.74 49.57 Elastic modulus (MPa) 2621.88 2417.04

As shown in Table 1, it can be confirmed that Example 1 is superior to Comparative Example 1 in tensile strength and elastic modulus. Specifically, Example 1 is judged to have improved mechanical properties because it contains carbon nanomaterials.

[Experimental Example 2] Evaluation of plating adhesion

In order to evaluate the plating adhesion of the separator molded body, a 10 mm wide scratch was made on the front part of the separator molded body manufactured in Examples 2 and 3, and the strength value obtained by peeling about 80 mm in the vertical direction using a pull gauge was measured. It is expressed in N/cm units. The number of tests was conducted three times per specimen, and the average value was taken as the plating adhesion value. The results are shown in Table 1 below.

Example 2 Example 3 Plating adhesion 8 12

As shown in Table 2, it can be confirmed that Example 3 has superior plating adhesion than Comparative Example 2. Specifically, Example 3 contains carbon nanomaterials (carbon nanotubes) in the conductive adhesive, so the plating adhesion is excellent. It is judged to have improved.

[Experimental Example 3] Performance evaluation of unit cell

The performance of the unit cell was evaluated using the separator specimens prepared in Example 3 and Comparative Example 2, and the results are shown in Table 3.

The performance evaluation conditions were: for the anode, the humidifier temperature was 71℃, the line heater temperature was 81℃, and the dew point temperature was 64.3℃; for the air electrode, the humidifier temperature was 69℃, the line heater temperature was 79℃, and the dew point temperature was 64.5℃. were measured, and the performance of all of them was evaluated in constant current mode at 100% relative humidity.

Example 3 Comparative Example 2 Current Density(A/cm) 0.5 0.5 Cell Voltage(V) 0.663 0.6824

As shown in Table 3, it can be seen that Example 3 and Comparative Example 2 show similar performance, and through this, the PEMFC unit cell specimen for fuel cell performance testing manufactured by the manufacturing method of the present invention can replace the existing specimen. It is believed that there is. Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art can realize that the present invention can be implemented in other specific forms without changing the technical idea or essential features of the present invention. You will be able to understand it. Therefore, the embodiments described above are illustrative in all respects and are not restrictive.

10: Separator plate molded body
20: concave portion
30: Adhesive part
40: Copper plating layer
A: Conductive adhesive

Claims (2)

A separator molded body printed with resin in the form of a separator plate using a 3D printer;
A concave portion formed by applying acetone to the surface of the separator molded body;
An adhesive portion formed by applying a conductive adhesive to the separator molded body on which the concave portion is formed and polishing the surface so that the conductive adhesive remains only in the concave portion;
It includes a copper plating layer formed through a copper plating step of plating copper metal on the separator molded body on which the adhesive portion is formed,
The resin is,
Based on 100 parts by weight of ABS (Acrylonitrile Butadien Styrene), it is a composite material containing 1 to 5 parts by weight of carbon nanomaterial consisting of one or more of carbon nanotubes, graphene, and carbon nanofibers,
The copper plating layer has a thickness of 20 to 80㎛,
The separator plate molded body that has completed the copper plating step has a thickness of 0.7 to 1.7 mm,
The adhesive part,
It is formed by buffing and polishing the surface of the separator molded body with an abrasive cloth,
The copper plating step is,
A PEMFC separator specimen for fuel cell performance testing, characterized by electroplating using copper salt and copper electrode plates, and adjusting the thickness of the copper plating layer according to the resistance value. According to paragraph 1,
The copper salt is,
A PEMFC separator specimen for fuel cell performance testing, characterized by using one of copper sulfate, copper chloride, copper oxide, copper methanesulfonate, and copper pyrophosphate.