KR101523949B1 - electrode for fuel cell using porous foam and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an electrode for a fuel cell using a porous foam capable of reducing lead time, improving work efficiency and strength of a product as well as reducing cost, and a method of manufacturing the same. The nickel foil is coated with a nickel metal and a ceramic mixed powder, and then the electrolyte powder is applied immediately and the electrolyte is impregnated into the pores by heating and pressing to shorten the preliminary process and the heat treatment process, The present invention relates to an electrode for a fuel cell using a porous foam capable of reducing manufacturing cost by improving workability as well as time, and a method of manufacturing the same.

Description

TECHNICAL FIELD The present invention relates to an electrode for a fuel cell using a porous foam,

The present invention relates to an electrode for a fuel cell and a method of manufacturing the electrode. More particularly, the present invention relates to an electrode for a fuel cell and a method of manufacturing the same, which can reduce lead time, improve work efficiency, To an electrode for a fuel cell using a porous foam and a manufacturing method thereof.

More particularly, the present invention relates to a method for manufacturing a nickel-metal composite, which comprises applying a nickel metal and a ceramic mixed powder to a porous nickel foil and then applying an electrolyte powder directly to the porous nickel foil to pressurize the electrolyte, thereby reducing the pre- The present invention relates to an electrode for a fuel cell using a porous foam capable of reducing the manufacturing cost by improving the lead time as well as workability by shortening the process and a manufacturing method thereof.

A fuel cell is a power generation system that generates electrical energy directly through the electrochemical reaction of the chemical energy of fuel, which is classified as highly efficient clean energy. Fuel cells include a molten carbonate fuel cell operating at a high temperature of 500 to 700 ° C, a solid oxide fuel cell operating at 700 ° C or higher, a phosphoric acid fuel cell operating at a low temperature of 200 ° C, and a polymer electrolyte fuel cell operating at a temperature of 100 ° C or lower It is classified.

Since the molten carbonate fuel cell (MCFC) in the fuel cell is operated at a high temperature of 650 ° C or higher, the electrochemical reaction rate is high, and nickel can be used instead of the platinum catalyst as the electrode material, Carbon monoxide, which acts as a poisonous substance, can also provide a variety of fuel selectivities, such as coal gas, natural gas, methanol, and biomass, as characteristics of a nickel electrode used as a fuel through a water gas conversion reaction.

In addition, the high temperature operation characteristics of the MCFC lead to an electrochemical reaction and a fuel reforming reaction simultaneously in the fuel cell stack. That is, it provides an advantage that an internal reforming mode can be adopted. This internal reforming type MCFC uses the calorific value of the electrochemical reaction for the reforming reaction, which is a direct endothermic reaction without a separate external heat exchanger. Therefore, the thermal efficiency of the entire system is further increased as compared with the externally modified MCFC, Lt; / RTI >

Such conventional internal reforming MCFCs are composed of repetitive lamination of separator / cathode / electrolyte / anode / internal reforming catalyst / separator.

The technologies related to such MCFCs are Patent Documents 1 to 4.

Patent Document 1 relates to an electrode using a clad material on which a nickel porous sheet is supported on both sides of a hydrogen absorbing alloy layer in which a hydrogen absorbing alloy powder has been hardened. In the manufacturing process of a negative electrode substrate for a nickel-hydrogen battery, And Patent Document 2 discloses a method of controlling the degree of microstructure and thickness flattening through a compression process for powder rearrangement, which is economical because the process is simple and the manufacturing cost is lower than that of the prior art, Patent Document 3 discloses a method for producing an electrode by dispersing a metal powder on a graphite plate by dry casting, compressing the cast powder, sintering the compacted powder, Electrode.

In addition, Patent Document 4 discloses a method in which metal powder containing filament-type nickel powder is spread and dried on a graphite plate, and then the dry-cast powder is compressed, and the compacted powder is heated at 650 to 950 And then sintered and pressurized.

The conventional method of manufacturing the electrode for a fuel cell performs a normal process as shown in FIG. That is, the nickel metal and ceramic are mixed, kneaded with an organic solvent, the mixed powder dough is flattened, the formed plate electrode is heat treated at a high temperature, and then the electrolyte is applied. After the electrolyte is applied, heat treatment is performed at a high temperature so that the electrolyte is evenly impregnated in the sintered body.

In the conventional method of manufacturing an electrode for a fuel cell having such a process, when a Ni metal powder is sintered, it is required to form micro pores and then to impregnate and impregnate an electrolyte powder (Li2CO3: K2CO3) having high conductivity into the pores A large pore size should be formed in order to smoothly impregnate the electrolyte powder. Accordingly, in order to produce a sintered body having a high porous structure, the sintering temperature must be lowered so that the bonding strength of the Ni metal powder is not high, but the strength is weakened.

Also, since the sintering temperature is low, there is a problem that when the fuel cell composed of such an electrode is operated at a high temperature for a long time, the structure of the electrode is collapsed due to oxidation behavior of the electrode, and the electrochemical performance is reduced. Furthermore, since the microstructure changes at high temperature due to the weak strength, there is a problem that the variation of the pore size is inhomogeneous in the intestine of the large-area electrode, and the distribution of the electrolyte is not uniform.

In addition, since the conventional electrode manufacturing method needs to perform two or more heat treatment steps, the equipment required for manufacturing the electrode becomes large, and time and labor are consumed so that productivity is low.

1. Japanese Patent Laid-Open No. 2000-30700 2. Korean Patent Publication No. 1044163 3. Korean Patent No. 0980209 4. Korean Patent No. 1047717

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell electrode using a porous foam having improved productivity by simplifying a manufacturing process and a method of manufacturing the same.

In addition, the present invention can be used to control the pore size contributing to the electrochemical activity by controlling the pore size of the nickel foam by using the porous nickel foam as a base material, so that it is easy to control the size of the pore, The present invention also provides an electrode for a fuel cell using the porous foam reinforced with a strength by acting as a single support, and a method of manufacturing the same.

In order to achieve the above object, the present invention provides a method for manufacturing a nickel-ceramic powder, which comprises uniformly coating a nickel-ceramic powder mixed with nickel and ceramics in pores of a porous metal foam, applying an electrolyte powder to the surface thereof, .

In addition, in the electrode of the present invention, it is preferable to use nickel as a porous metal foam in order to accelerate the electrochemical reaction rate of the porous metal foam, and it is preferable to use a metal foam having a mesh of 100 to 500 μm desirable.

According to another aspect of the present invention, there is provided a method of manufacturing an electrode for a fuel cell using a porous foam, the method comprising: preparing a porous metal foam; mixing nickel and ceramic powder; Uniformly applying the nickel-ceramic mixed powder to the metal foams; Pressing the nickel-ceramic mixed powder into a rolling machine so as to fill the pores of the metal foam; A step of applying an electrolyte powder to the surface of the nickel-ceramic mixed powder filled in the pores of the metal foam; and a heat treatment step of heating the electrolyte powder so as to be impregnated between the nickel-ceramic mixed powders.

In this preparation method, it is preferable that the porous metal foam is further subjected to a pretreatment step of pressing with a rolling machine to adjust the pore size to a mesh of 100 to 500 탆.

The heat treatment temperature in the heat treatment step is 600 to 750 占 폚, and the treatment time can be 8 to 12 hours.

The present invention has the effect of easily controlling the size of the pores by controlling the pore size of the nickel foam by using the porous nickel foam as a base material.

Further, since the nickel foil serves as a support, it is possible to provide a rigid electrode which is not broken easily.

In addition, nickel metal and ceramic powder in the form of powder are applied to the porous pores of the nickel foam, and the pretreatment process and the heat treatment process are reduced by performing the heat treatment in the state where the electrolyte is applied, thereby simplifying the entire process. There is also an effect that can be high.

Fig. 1 is a graph showing the relationship between the degree of fixation showing an example of a conventional electrode manufacturing process for a fuel cell
FIG. 2 is a process diagram showing a process of manufacturing an electrode for a fuel cell using the porous foam according to the present invention
3 is an enlarged photograph of a metal foam for producing electrodes for a fuel cell according to the present invention
4 is a process diagram showing a process of processing a metal foam

Hereinafter, an electrode for a fuel cell using the porous foam according to the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

The present invention is to provide a fuel cell electrode having enhanced strength and productivity by simplifying the manufacturing process, and is characterized by using the porous metal foam 100 as a substrate.

That is, the pores 100h formed in the porous metal foam 100 are filled with the nickel-ceramic mixed powder 200 in which nickel and ceramics are mixed to stabilize the nickel-ceramic mixed powder, Ceramic mixed powder 200 and the electrolyte powder 300 by adjusting the size of the pores of the porous metal foam 100 by impregnating and impregnating the porous metal foam 100 with the porous metal foam 100, will be.

In addition, since the porous metal foam 100 serves as a support to hold the nickel-ceramic mixed powder 100 and the electrolyte powder 300, it is possible to provide an electrode which is not easily broken even by an external impact.

As described above, the electrode for a fuel cell using the porous foam according to the present invention is used as an electrode for a molten carbonate fuel cell. Since the electrode is operated at a high temperature of 650 ° C or higher, the porous metal foam 100 ) Is preferably made of nickel.

As shown in FIG. 3, the porous metal foam 100 is preferably a sponge-like metal having a large number of pores. The porous metal foam 100 is preferably thicker than the thickness of a typical electrode for a fuel cell and has a large pore size.

The metal foam 100 is formed by supplying a gas and a foaming agent to molten metal heated and melted to distribute bubbles and cooling molten metal in a state where bubbles are distributed. The metal foam used in the present invention is nickel The gas and the foaming agent are supplied while cooling the bubbles in a distributed state.

Such a metal foam 100 can control the size and distribution of pores formed by controlling the amount of gas to be injected and the amount of the foaming agent. However, since the metal foam 100 needs to be supplied in a desired specification in order to be used in manufacturing the electrode, . Accordingly, the metal foam 100 constituting the present invention can be used by selecting a foamed metal having a pore of a desired size in consideration of the degree of impregnation of the electrolyte.

It is preferable that the metal foam 100 has a specific thickness in accordance with the thickness of the electrode for a fuel cell. However, since it is difficult to precisely match the thickness of the metal foam 100, desirable. That is, it is preferable to select one having a large pore and a thicker thickness than those required for manufacturing the electrode, and press it with a rolling machine to adjust the thickness and pore size as shown in FIG.

Since the size of the pores formed in the metal foam 100 constituting the present invention affects the degree of integration of the electrolyte powder, in order to allow the electrolyte powders to be collected in an optimal state, Preferably, the size of the pores may be from 100 to 500 μm, and the porosity may be from 25 to 90%.

The nickel-ceramic mixed powder 200 filled with the nickel-ceramic mixed powder 200 is filled in the pores of the metal foam 100, and the nickel-ceramic mixed powder 200 is filled in the pores to form a plate shape. As described above, the pressing method may be a rolling method using a rolling machine, or a method of pressurizing the upper and lower surfaces with a wide plate.

The nickel-ceramic powder 200 comprises 20 to 60% by weight of nickel (Ni) and 40 to 80% by weight of ceramic. If the content of the ceramic is excessively high, the sinterability is decreased. When the content of the nickel powder is increased, the sinterability is improved but the creep phenomenon occurs and the porosity decreases.

As the ceramic powder, at least one of an aluminum alloy and a chromium alloy may be used, that is, either an aluminum alloy or a chromium alloy may be used, or a mixture thereof may be used.

On the surface of the nickel-ceramic powder, the electrolyte is impregnated between the nickel-ceramic powders by heating with the electrolyte powder 300 directly coated.

The electrolyte powder 300 may be used in an amount of 10 to 150 parts by weight based on 100 parts by weight of the nickel-ceramic powder 200. The amount of the electrolytic powder can be further increased. The electrolyte powder may have a size of 0.1 to 10 탆 and may be one of two or more carbonates from the group consisting of Li, Na, K, Rb, Cs, Gd, Ca, Sr, Ba and Mg.

The electrode for a fuel cell using the porous foam according to the present invention may have a thickness of 0.3-1.0 mm, a pore size of 1-15 μm and a porosity of 30-90% It is preferable that the electrode has a porosity of 60-80% when the electrode is an air electrode and a porosity of 40-60% when the electrode is a fuel electrode.

The method of manufacturing an electrode for a fuel cell according to the present invention comprises: preparing a porous metal foam; mixing nickel and ceramic powder; Uniformly applying the nickel-ceramic mixed powder to the metal foams; Pressing the nickel-ceramic mixed powder into a rolling machine so as to fill the pores of the metal foam; A step of applying an electrolyte powder to the surface of the pore-filled nickel-ceramic mixed powder of the metal foam; and a heat treatment step of heating the electrolyte powder so as to be impregnated between the nickel-ceramic mixed powders.

First, the step of preparing the porous metal foam is to simply cut the foamed metal made of nickel or press it with a rolling machine to have a desired thickness and pore size, as described above. If the prepared metal foam has a desired pore and thickness, it can be used as it is. However, if the pore size is large and thick, it is pressurized by using a rolling machine or the like to reduce the size and reduce the size of pores. At this time, the size of the pores controlled by the pressurization may be a mesh of 100 to 500 μm.

The preparation of the nickel and ceramic powder may be performed by selecting powders having a desired particle size among powders that are conventionally provided, or by re-grinding the powder to a desired particle size. The prepared nickel and ceramic powders are mixed at a predetermined ratio, Ceramic mixed powder is made. At this time, as described above, the mixing ratio of nickel and ceramic powder is 20 to 60% by weight of nickel and 40 to 80% by weight of ceramic. The mixing method may be any one or more of ball milling, milling and mixer.

Spray the mixed nickel-ceramic mixed powder evenly over the porous metal foam. As a method of spraying the nickel-ceramic mixed powder on the upper surface of the metal foam, a tape casting method or a powder spraying device can be used.

Since the nickel-ceramic mixed powder sprayed on the metal foam is not adhered to the metal foam but is not sufficiently impregnated into the pores of the metal foam, a rolling machine is used to uniformly impregnate the metal-foam with the nickel- To apply pressure. Of course, other devices than the rolling machine can be used as a means of applying pressure. At this time, vibration may be applied so that the nickel-ceramic mixed powder is uniformly filled in the pores of the porous metal foam.

When the nickel-ceramic mixed powder is adhered to the pores of the metal foam by pressurization, the electrolyte powder is applied on the nickel-ceramic mixed powder. When the nickel-ceramic mixed powder is stabilized to a certain extent in the state of being filled in the pores of the porous metal foam, the electrolyte powder is coated thereon. In the state where the nickel-ceramic mixed powder is stabilized, the porous metal foams and the nickel-ceramic mixed powders are bonded to each other such that the nickel-ceramic mixed powders are collected on one side and the thickness is not changed during transportation. The amount of the electrolyte powder to be applied may be about 10 to 150 parts by weight based on 100 parts by weight of the nickel-ceramic powder 200.

When the electrolyte powder is applied to the nickel-ceramic mixed powder coating surface, it is put into a high-temperature furnace (crucible or the like) and heat-treated to harden the electrolyte powder between the nickel-ceramic mixed powders. In this case, the heating temperature is 600 to 750 ° C. and the treating time is about 8 to 12 hours. When the heating temperature is low, the electrolyte is not sufficiently melted and the impregnation rate is lowered, and the mechanical strength is lowered. When the heating temperature is too low, neck growth may occur between the particles and mechanical coupling may occur. It is preferable that sintering is carried out within the range.

100: Porous metal foam
200: Nickel-ceramic mixed powder
300: electrolyte powder

Claims (11)

delete delete delete delete delete delete Preparing a porous metal foam; Mixing nickel and ceramic powder; Uniformly applying the nickel-ceramic mixed powder to the metal foams; Pressing the nickel-ceramic mixed powder into a rolling machine so as to fill the pores of the metal foam; Applying an electrolyte powder to a surface of a pore-filled nickel-ceramic mixed powder of a metal foam; And a heat treatment step of heating the electrolyte powder so as to be impregnated between the nickel-ceramic mixed powders,
Wherein the porous metal foam has pores larger than the pores of the electrode to be manufactured and is formed of a thick metal foam, and the nickel-ceramic mixed powder is filled in the pores by the pressing of the rolling machine, Is adjusted,
Wherein the sintering of the nickel-ceramic powder and the impregnation of the electrolyte powder are simultaneously performed in the heat treatment step.
8. The method of claim 7,
Wherein the porous metal foam is further subjected to a pretreatment step of pressing the porous metal foam with a rolling machine to adjust the pore size to a mesh of 100 to 500 mu m.
8. The method of claim 7,
Wherein the heat treatment temperature in the heat treatment step is 600 to 750 ° C. and the treatment time is 8 to 12 hours.
8. The method of claim 7,
Wherein the ratio of nickel (Ni) and ceramic mixed in the nickel-ceramic powder mixing step is 20 to 60% by weight of nickel and 40 to 80% by weight of ceramic.
8. The method of claim 7,
Wherein the ceramic powder is at least one of an aluminum alloy and a chromium alloy.

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