KR20090028941A - Polymer-metal complex of end plate for fuel cell and manufacturing method for it - Google Patents

Abstract

An end plate of a polymer-metal complex structure for a fuel cell is provided to improve mechanical strength due to the insertion of a metal frame and to minimize the deformation while maintaining excellent insulating property, chemical resistance, hydrolysis resistance, and lightness. An end plate(12) of a polymer-metal complex structure for a fuel cell includes a metal frame(10) inserted into the inside, and a polymer-glass fiber complex structure surrounding the outer surface of the metal frame. The complex structure has a flat or stress-reinforcing rib structure.

Description

Polymer-metal complex of end plate for fuel cell and manufacturing method for it}

The present invention relates to a polymer-metal composite structure end plate for a fuel cell and a method for manufacturing the same, and more particularly, a fuel in which a polymer structure and a metal frame are integrated by inserting a metal frame and molding in a single process during melt molding of the polymer structure. It relates to a polymer-metal composite structure end plate for a battery and a method of manufacturing the same.

In general, a fuel cell system is a type of power generation system that converts chemical energy of a fuel directly into electrical energy.

The fuel cell system includes a fuel cell stack that generates electric energy largely, a fuel supply system for supplying fuel (hydrogen) to the fuel cell stack, and an air supply for supplying oxygen in the air, which is an oxidant required for an electrochemical reaction, to the fuel cell stack. The system consists of a heat and water management system that removes the reaction heat from the fuel cell stack to the outside of the system and controls the operating temperature of the fuel cell stack.

With such a configuration, the fuel cell system generates electricity by an electrochemical reaction by hydrogen, which is a fuel, and oxygen in the air, and discharges heat and water as reaction byproducts.

The fuel cell stack is a main power supply source of a fuel cell vehicle, and is an apparatus for producing electricity by receiving oxygen in air and hydrogen as fuel. In addition, a fuel cell stack applied to an automobile is composed of about 400 unit cells or more, and each unit cell forms a voltage of about 0V to 1.33V.

The fuel cell stack, which is widely used for automobiles, is a high-density solid polymer electrolyte fuel cell (Proton Exchange Membrane Fuel Cell, PEMFC).

FIG. 1 is a perspective view showing a stack structure of a polymer electrolyte membrane fuel cell which is generally used. A combination of a membrane electrode assembly (MEA) and a gas diffusion layer 1 is inserted between a separator 2 having a hydrogen electrode and an air electrode. To form a unit cell, and the unit cells are repeatedly stacked to form a stack structure.

In the outward direction of the separating plate 2, the current collecting plate 3, the insulating plate 4, and the end plates 5, 6 are positioned at both ends of the stack so that the cells are properly fastened.

Two types of end plates are used, i.e., through-type (5) and non-penetrating (6). The through-type end plates (5) have hydrogen, oxygen and cooling water manifolds formed on the non-through-type end plates (6). In addition, the manifold serves to efficiently supply reaction gases and cooling water.

The end plate should be able to maintain a uniform fastening of the stack and a constant fastening pressure between the cells, for this purpose it should have excellent mechanical strength, airtightness, chemical resistance, hydrolysis resistance and the like.

By the way, conventionally used as a stack end plate by machining a metal material such as stainless steel alone, in this case, in this case, reactants such as hydrogen, air, etc. used in the electrochemical reaction of the fuel cell stack, generated water and cooling water, etc. This can cause corrosion of the end plate.

In particular, existing research reports [R. C. Makkus, A. H. H. Janssen, F. A. de Bruijn, R. Mallant, J. Power Sources, 86, 274 (2000); A. Pozio, R. F. Silva, M. De Francesco, L. Giorgi, Electrochim. According to Acta, 48, 1543 (2003)], when various metal corrosion products are generated and eluted, they penetrate into the polymer electrolyte membrane electrode assembly inside the stack and act as a contaminant, and the electrochemical performance of the fuel cell stack may be greatly reduced.

In addition, the use of metal materials increases the weight, there is a problem that the production speed is lowered by the machining and the manufacturing cost is rapidly increased.

In particular, since it is difficult to give electrical insulation at the end of the stack when using a metal material, an insulating plate is inserted between the current collector plate and the end plate to secure electrical insulation, and to further enhance corrosion resistance and insulation such as chemical resistance and hydrolysis resistance. The endplates are coated with an expensive protective material.

However, in this case, additional insulation plate insertion and end plate protective coating have to be applied, which leads to complicated manufacturing process and increased manufacturing cost. In addition, coating coating may be damaged due to uneven coating or unexpected scratches during long-term use, resulting in dissolution of metal corrosion products. There are drawbacks to this.

In order to solve such problems, US Patent Nos. 6190793 and 6764786 disclose an end plate manufactured using a non-metallic polymer material or the like.

However, the polymer material alone has advantages such as light weight, insulation, chemical resistance, and mass production by molding, but has lower mechanical strength and higher strain due to temperature than metal end plates such as stainless steel of the same structure. As a result, the clamping pressure acting on the MEA is uneven and it is difficult to maintain airtightness.

In addition, when only polymer materials are used, the thickness of the end plate must be increased to maintain mechanical strength or a certain level of deformation above a certain level. In this case, uniform polymer molding itself is difficult, and the volume of the stack is increased, thereby outputting the fuel cell stack. There is a problem that the density is reduced and it is difficult to efficiently deploy with other fuel cell operators.

SUMMARY OF THE INVENTION The present invention has been made in view of the above. As a result, a metal frame is used as an insert, and the polymer material is melt-molded (overlaid) on the entire outer surface of the metal frame, thereby providing excellent insulation, chemical resistance, and hydrolysis resistance. To provide a polymer-metal composite structure end plate for fuel cells and a method of manufacturing the same, which can improve mechanical strength and minimize deformation due to the insertion of a metal frame while maintaining the existing advantages of polymer materials such as light weight and mass productivity. The purpose is.

In order to achieve the above object, the present invention provides a polymer-metal composite structure end plate for a fuel cell,

Metal frame inserted therein, characterized in that it comprises a polymer-glass fiber composite structure surrounding the outer surface of the metal frame.

In a preferred embodiment, the composite structure is characterized in that it consists of a flat plate or stress relief rib structure.

In a more preferred embodiment, the metal frame is characterized in that consisting of a flat plate or stress relief rib structure.

In addition, the composite structure is characterized in that it comprises 20 to 100 parts by weight of thermoplastic polymer, 0 to 80 parts by weight of glass fiber.

In a more preferred embodiment, the composite structure is characterized in that it comprises 60 to 80 parts by weight of thermoplastic polymer, 20 to 40 parts by weight of glass fiber.

In addition, the thermoplastic polymer is polyamide, polyphenylene sulfide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyether ketone, polyether ether ketone, poly Any one selected from ether ether ketone ketone, polyethylene, and polypropylene, using homopolymers or random / branch / block / alternative copolymers of each of the above polymers alone, or the polymers of at least one other thermoplastic / thermosetting / rubber It is characterized by being in the form of a blend with a polymer or mixed with organic / inorganic materials.

In addition, the polyamide polymer is characterized by consisting of at least one polyamide selected from aliphatic, aromatic and semi-aromatic.

In addition, the metal frame is characterized in that any one selected from stainless steel, aluminum and aluminum alloy.

Another aspect of the present invention is a method for producing a polymer-metal composite structure end plate for a fuel cell,

Manufacturing a metal frame for inserting an end plate based on stainless steel; Inserting a metal frame into the injection molding machine; And injection molding the polymer and the glass fiber composite material on the metal frame so as to cover the entire outer surface of the metal frame.

In a preferred embodiment, the molding method of the polymer and glass fiber composite is characterized in that it consists of a process selected from injection molding, compression molding and extrusion molding or a process in which two or more are mixed.

In a more preferred embodiment, the polymer and glass fiber composite material is made by injection molding, injection molding machine melt temperature is 310 ~ 370 ℃, molding mold temperature is 60 ~ 170 ℃ characterized in that the molding mold time for 1 ~ 60 minutes do.

In addition, the polymer and glass fiber composite material is made by injection molding, the injection molding machine melt temperature is 320 ~ 335 ℃, molding mold temperature is characterized in that the molding mold time is made for 5 to 20 minutes at 130 ~ 155 ℃.

As described above, according to the polymer-metal composite structure end plate for a fuel cell according to the present invention and a method for manufacturing the same, a metal frame having excellent mechanical strength is inserted therein, and a light weight, insulation, chemical resistance, and water resistance are provided on the outer surface. By adding a polymer material having excellent degradability and the like, the weight is significantly reduced compared to the end plate of the conventional metal alone material, and the mass production can be efficiently carried out by the molding (molding) process, and the surface of the metal end plate is protected. Since there is no need for coating, it can contribute to simplifying the process and reducing the cost.

In addition, since the reactant and the generated water do not come into contact with the metal, it is possible to prevent the MEA contamination due to the elution of the metal corrosion product even when used for a long time.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cutaway perspective view showing a through-type end plate according to an embodiment of the present invention, Figure 3 is a cutaway perspective view showing a non-penetrating end plate according to an embodiment of the present invention.

The present invention provides a metal frame (10, 11) excellent in mechanical strength, and a composite structure end plate that can have all the advantages of a polymer material excellent in insulation, chemical resistance and light weight.

The end plates 12 and 13 according to the embodiment of the present invention have a structure in which the composites 14 and 15 of the polymer and glass fiber having excellent meltability are formed on the outer surfaces of the metal frames 10 and 11 therein. Is done.

In this case, as the molding method of the composite material (14, 15), it is possible to use not only injection molding but also compression molding and extrusion molding according to the polymer melt molding process.

The end plates 12 and 13 may be applied to both the through-type end plate 12 in which the manifold, which is a supply passage for the reactor body and the cooling water, and the non-through end plate 13 simply supporting the unit cell.

The end plates 12 and 13 of the polymer-metal composite structure may be used at the same positions as the conventional metal through end plates and the non-penetrating end plates to fasten the unit cell.

The composite structure may be optimally designed to resist strong fastening force and deformation of the fuel cell stack, and thus may be manufactured to have a flat plate or a structure having stress reinforcing ribs.

The end plate polymer material is required to be excellent in insulation, hydrolysis resistance, meltability, mass production, etc., and to have mechanical properties such as bending strength, impact strength, and tensile strength, and to be low in manufacturing cost.

Polymer materials that can realize these characteristics include polyamide, polyphenylene sulfide, polyimide, polyether imide, polycarbonate, polyphenylene ether ( Polyphenylene ether, Polyethylene terephthalate, Polybutylene terephthalate, Polyetherketone, Polyetheretherketone, Polyetheretherketoneketone, Polyetheretherketoneketone ) And polypropylene.

As the polymer substrate, homopolymers or random / bran / block / alternating copolymers of the above polymers may be used alone, or the polymer may be used in one or more kinds of thermoplastics. (Thermoplastic) / Thermoset / Rubber It can be used in the form of blends with polymers or mixed with organic / inorganic materials. The polymer substrate may be mixed with 0 to 80 parts by weight of glass fiber, more preferably 20 to 40 parts by weight, in order to improve various physical properties such as mechanical properties depending on the required use.

Because, when the glass fiber is added in excess of 80 parts by weight, it is very difficult to express the molding processability and physical properties inherent in the polymer substrate, more preferably, when the glass fiber is added in less than 20 parts by weight of the mechanical properties of the polymer substrate This is because the improvement is difficult to be achieved sufficiently, and when added in excess of 40 parts by weight, the molding processability and the ductility of the polymer substrate are lowered, making it difficult to achieve the target performance.

As the metal frames 10 and 11 for the polymer-metal composite end plate of the present invention, various metal materials such as stainless steel such as SS316, SS316L, and SS304, aluminum, and aluminum alloy may be used.

In addition, the metal frames 10 and 11 may be manufactured in a structure having a flat plate or a stress reinforcing rib.

The present invention is intended to be described in more detail based on a polyamide-based excellent physical properties and economical efficiency for the end plate of the polymer material, but the present invention is not limited thereto.

Example

In general, polyamides may be classified into aliphatic, aromatic and semi-aromatic polyamides according to their molecular structure.

Here, one embodiment of the present invention is based on a semi-aromatic polyamide suitable for end plate melt molding by properly combining the advantages of aliphatic polyamide and aromatic polyamide, and a half echo with 35 parts by weight of glass fiber appropriately mixed Based on the group polyamide / glass fiber composites 14 and 15, a composite structure for end plates having stress-reinforced ribs was produced.

In addition, an embodiment of the present invention manufactured the end plate insertion metal frame (10, 11) having a flat plate-based structure based on SS304, which is a general stainless steel.

When forming the polymer-metal composite end plate, the flat SS304 metal frames 10 and 11 were placed in an injection molding machine, and then semi-aromatic polyamide / glass fiber composites 14 and 15 were injection molded on the metal frame. .

The injection molding machine melt temperature during the polymer injection molding may be set within the range of 310 ~ 370 ℃, more preferably at 320 ~ 335 ℃ to optimize the semi-aromatic polyamide / glass fiber composite to be sufficiently evenly melted.

This is because when the injection machine melt temperature is less than 310 ° C., it is very difficult to impart sufficient fluidity to the composite, so that the injection molding processability is drastically reduced, and when it exceeds 370 ° C., injection molding instability due to excessive fluidity and the polymer substrate itself This is because it may cause decomposition, and if it is less than 320 ° C., the injection molding processability of the composite material may not be sufficiently expressed, and if it exceeds 335 ° C., induction of injection molding instability will start.

In particular, in order to express the optimum properties of the crystalline high performance engineering composite material, the molding mold conditions for performing crystallization and solidification are very important.

That is, one embodiment of the present invention can be molded under the conditions of 1 to 60 minutes in the range of 60 ~ 170 ℃ the molding mold temperature is relatively high so as to sufficiently express the polymer properties, and minimize deformation after molding, more preferably Was molded by optimizing the molding conditions in 5 to 20 minutes at 130 ~ 155 ℃ temperature.

If the molding conditions are less than 60 ℃ and less than 1 minute, the mobility of the polymer molecular chains in the composite is very insufficient and the time for the chains to crystallize is difficult enough crystallization, more than 170 ℃ and 60 minutes This is because the thermodynamic driving force required for crystallization is very low and the injection molding cycle time is increased, resulting in a very low productivity.In the case of 130 ° C and less than 5 minutes, the molecular chain fluidity and crystallization of the polymer If the crystallization is difficult due to lack of time, and the temperature exceeds 155 ° C and 20 minutes, the crystallization is insufficient due to the lack of thermodynamic impulse and the productivity begins to be insufficient due to the increase of the molding cycle time.

4 shows the actual stack cell fastening of through and non-penetrating end plates consisting of a semi-aromatic polyamide / glass fiber composite structure and a stainless steel SS304 metal frame molded under the above injection conditions.

When stacking the actual fuel cell cells 16 between the through-type and non-penetrating polymer-metal composite structure end plates 12 and 13 according to an embodiment of the present invention, the internal metal frames 10 and 11 are stacked. It is possible to prevent deformation of the end plate, and the polymer / glass fiber composite material (14, 15) as shown in Figure 5 reduced the weight by 46% compared to the existing metal end plate is easy to tighten, The process is simplified because no protective material coating process is required, resulting in excellent mass production and drastically reducing manufacturing costs.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

1 is a perspective view showing a fuel cell stack structure according to the prior art,

Figure 2 is a cutaway perspective view showing a through-type end plate according to an embodiment of the present invention,

Figure 3 is a cutaway perspective view showing a non-penetrating end plate according to an embodiment of the present invention,

4 is a side view showing a fuel cell stack according to an embodiment of the present invention;

5 is a graph showing the weight reduction of the end plate according to an embodiment of the present invention compared to the existing metal end plate.

<Description of the symbols for the main parts of the drawings>

10,11: metal frame 12: through end plate

13: non-penetrating end plate 14,15: polymer / glass fiber composite

16 unit battery

Claims (12)

In the polymer-metal composite end plate for a fuel cell, A polymer-metal composite structure end plate for a fuel cell, comprising a metal frame inserted therein and a polymer-glass fiber composite structure surrounding the outer surface of the metal frame. The method according to claim 1, The composite structure is a polymer-metal composite end plate for a fuel cell, characterized in that consisting of a flat plate or a stress reinforcing rib structure. The method according to claim 1, The metal frame is a polymer-metal composite structure end plate for a fuel cell, characterized in that consisting of a flat plate or a stress reinforcing rib structure. The method according to claim 1, The composite structure is a polymer-metal composite structure end plate for a fuel cell, characterized in that it comprises 20 to 100 parts by weight of thermoplastic polymer, 0 to 80 parts by weight of glass fiber. The method according to claim 1, The composite structure is a polymer-metal composite structure end plate for a fuel cell, characterized in that it comprises 60 to 80 parts by weight of thermoplastic polymer, 20 to 40 parts by weight of glass fiber. The method according to claim 4, The thermoplastic polymer is polyamide, polyphenylene sulfide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyether ketone, polyether ether ketone, polyether ether Any one selected from ketone ketone, polyethylene and polypropylene, and use the homopolymer or random / branch / block / alternative copolymer of each of the above polymers alone, or use the polymer with one or more other thermoplastic / thermosetting / rubber polymers. A polymer-metal composite end plate for a fuel cell, characterized in that it is blended or mixed with organic / inorganic materials. The method according to claim 6, The polyamide polymer is a polymer-metal composite end plate for a fuel cell, characterized in that composed of at least one polyamide selected from aliphatic, aromatic and semi-aromatic. The method according to claim 1, The metal frame is a polymer-metal composite structure end plate for a fuel cell, characterized in that any one selected from stainless steel, aluminum and aluminum alloy. In the manufacturing method of polymer-metal composite structure end plate for fuel cell, Manufacturing a metal frame for inserting an end plate based on stainless steel; Inserting a metal frame into the injection molding machine; And Injection molding the polymer and the glass fiber composite material on the metal frame to cover the entire outer surface of the metal frame; Method for producing a polymer-metal composite structure end plate for a fuel cell comprising a. The method according to claim 9, The molding method of the polymer and glass fiber composite material is a method for producing a polymer-metal composite structure end plate for a fuel cell, characterized in that the injection molding, compression molding and extrusion molding of any one selected process or a mixture of two or more. The method according to claim 10, The polymer and glass fiber composite material is made by injection molding, and the injection molding machine melt temperature is 310 ~ 370 ℃, molding mold temperature is 60 ~ 170 ℃, the polymer-metal for fuel cell, characterized in that for 1 to 60 minutes Method of manufacturing a composite end plate. The method according to claim 10, The polymer and glass fiber composite material is made by injection molding, and the injection molding machine melt temperature is 320 ~ 335 ℃, molding mold temperature is 130 ~ 155 ℃ for the molding cell time, the polymer-metal for fuel cell, characterized in that made for 5 to 20 minutes Method of manufacturing a composite end plate.

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