KR100774468B1 - Fuel cell, electrode catalyst and electrode for fuel cell - Google Patents

Abstract

The present invention relates to a fuel cell, and more particularly, to a fuel cell using a hydrogen storage alloy as an electrode, the fuel electrode comprising a hydrogen storage alloy coated with nickel; By providing a fuel cell, characterized in that it comprises an anode provided between the fuel electrode and the electrolyte portion, the fuel cell according to the present invention has the advantage that can be supplied stable power even for a long time.

Description

FUEL CELL, ELECTRODE CATALYST AND ELECTRODE FOR FUEL CELL}

The present invention relates to a fuel cell, and more particularly, to a fuel cell using a hydrogen storage alloy as an electrode.

A fuel cell refers to a cell that directly converts chemical energy generated by oxidation of a fuel such as hydrogen into electrical energy.

1 is a schematic view showing an example of a general fuel cell, in which a fuel cell generally includes a fuel electrode (anode) 14 and an oxide electrode (cathode) 16 disposed with an electrolyte 12 interposed therebetween.

In the fuel cell having the structure described above, fuel such as hydrogen is supplied to the fuel electrode 14 through the fuel supply pipe 13, and an oxidant such as oxygen or air is supplied to the anode 16 through the oxidant supply pipe 17. do. At this time, in the anode 14, the oxidation reaction occurs with the release of electrons through the catalyst. Electrons generated at the anode 14 are transferred to the cathode 16 via a load 18 connected to the anode 14 and the cathode 16. In the negative electrode 16, the reduction reaction occurs along with the electrons transferred through the catalyst, thereby reducing the oxidizing agent. Meanwhile, cations / anions are transferred from the positive electrode 14 to the negative electrode 16 / the negative electrode 16 to the positive electrode 14 through the electrolyte 12 installed between the positive electrode 14 and the negative electrode 16.

In particular, when the fuel is used as hydrogen, while the fuel cell is operating, ionization of hydrogen ions H ⁺ and electrons e ⁻ proceeds at the anode 14, and H ⁺ generated at the anode 14 passes through an electrolyte. Moving to the cathode 16 and electron e ⁻ is transferred to the external load 18 via the anode 14. In the negative electrode 16, H ⁺ delivered through the electrolyte 12 reacts with oxygen in the air to generate water together with the heat of reaction. This is represented by the chemical reaction equation as follows.

Anode / Anode:

Oxide / Cathode:

Total Reaction:

In general, a fuel cell has a load connected to the positive electrode 14 and the negative electrode 16, and when the fuel cell is operated, electrons e ⁻ are continuously generated at the positive electrode 14 so that the negative electrode 16 passes through the load. ), That is, electrons are transferred from the positive electrode 14 to the negative electrode 16 to generate a current capable of operating an electric device or the like.

Meanwhile, as the anode of the fuel cell, a hydrogen storage alloy such as metal hydride (MH) is used in accordance with trends of high energy density, small weight, and long life, and when a hydrogen storage alloy is used, pollution-causing such as cadmium is used. The absence of material has the advantage of greatly reducing pollution.

By the way, the fuel cell usually requires a stable supply of power for a long time, depending on the material and characteristics of the electrode constituting the positive electrode or the negative electrode has a great effect on the life and output of the fuel cell.

In order to increase the efficiency and extend the life of fuel cells, various methods regarding electrodes have been proposed, for example, Japanese Patent Application Laid-Open No. 2002-246039 and International Patent Application Publication No. WO01 / 68246.

However, the fuel cells presented in the above documents are not only difficult to manufacture, but also incompletely bonded to the catalyst support member to which the catalyst in powder form is attached, and thus are separated from the catalyst support material, thereby leaving the efficiency and life of the electrode. It has a problem of shortening.

An object of the present invention is to solve the above problems, it is possible not only to maintain a stable performance continuously, but also easy to combine with the catalyst support material to which the catalyst is attached fuel cell, electrode catalyst and electrode of the fuel cell To provide.

The present invention was created in order to achieve the object of the present invention as described above, the fuel cell according to the present invention is a fuel electrode made of a hydrogen storage alloy coated with nickel; And an oxide electrode provided with the fuel electrode and the electrolyte portion interposed therebetween.

In another aspect, the present invention provides a catalyst for an electrode comprising a hydrogen storage alloy coated with nickel on a surface of an electrode of a fuel cell including a fuel electrode and an anode provided between the fuel electrode and the electrolyte.

In another aspect, the present invention provides a fuel cell electrode made of the electrode catalyst as described above.

1 is a schematic view showing the configuration of a typical fuel cell.

2 is an enlarged view of a catalyst for an electrode according to the present invention.

3 is an enlarged view illustrating a state in which the catalyst of FIG. 2 is cut.

4 is an enlarged view illustrating the enlarged view of FIG. 3.

5A, 5B and 5C are graphs showing the components of points 1, 2 and 3 of FIG. 2, respectively.

6 is a graph showing a current density-voltage relationship equation of a fuel cell using a catalyst for electrodes according to Examples and Comparative Examples of the present invention.

Hereinafter, a fuel cell, an electrode catalyst, and a fuel cell electrode according to the present invention will be described in detail with reference to the accompanying drawings.

The fuel cell according to the present invention is characterized in that it comprises a fuel electrode (anode) consisting of a hydrogen storage alloy coated with nickel, and an anode (cathode) provided between the fuel electrode (anode) and the electrolyte therebetween.

The electrode constituting the positive or negative electrode is composed of a catalyst for promoting oxidation of a fuel such as hydrogen, a reduction reaction of an oxidant such as oxygen or air, and a catalyst support material for bonding the catalyst to form an electrode.

The catalyst support material may be a metal material such as nickel or a nickel alloy, and may be used together with a binder such as PTFE in consideration of mechanical properties. In particular, when the catalyst support material is a nickel or nickel alloy metal material, the electrode catalyst according to the present invention coated on the surface with nickel is stably attached to the catalyst support material and separated from the catalyst support material during operation of a fuel cell. There is an advantage that can be prevented.

As the catalyst constituting the electrode, metal hydride (MH) is used as a hydrogen storage alloy.

As the metal hydride, an AB ₅ based alloy based on LaNi ₅ , MmNi ₅ (Mm; misch metal; a mixture of rare earth metals), an AB ₂ based alloy mainly containing a C14 or C15a Laves phase, and the like are used. Here, AB _{5 type} alloy, AB _{2 type} alloy, etc. are a single type alloy which substituted a part of La or Ni with another element. That is, Zr or Ti is used as the A element, and Ni, V, Mn, Cr, Al, and the like are used as the B element.

On the other hand, the catalyst can be configured in various forms, and in particular, it must be spherical in a form that can increase the area in contact with the fuel, such as hydrogen. That is, the catalyst may be implemented as fine powder, fine fibers, porous bodies, and the like. Of course, the catalysts are attached to the catalyst support material to form one electrode, thereby forming one electrode.

The catalyst used for the electrode of the fuel cell according to the present invention is usually used for a fuel electrode (anode), but can also be used for an anode (cathode).

Hereinafter, an embodiment of a fuel cell, an electrode catalyst, and a fuel cell electrode according to the present invention will be described.

Example

Metal hydride was used as the electrode catalyst, MH1 of Zr _0.9 Ti _0.1 Cr _0.55 Fe _1.45 (wt%, 41.73, 2.44, 14.54, 41.28), which is AB ₂ series alloy, and Zr _0.9 Ti _0.1 Mn _0.6 V _0.2 Co _0.1 MH 2 with Ni _1.1 (wt%, 40.93, 2.39, 16.46, 5.08, 2.94, 32.2) was used.

Then, the nickel metal hydride was coated in a powder form while immersing in a solution containing nickel maintaining a constant pH for a predetermined time. That is, 10 g / l of CO ₃ · Ni (OH) ₂ · 4H ₂ O (nickel carbonate-basic) and 5 g / l of C ₆ H ₅ O ₇ Na ₃ · H _{2 in the} form of powder first and one solution consisting of O (sodium citrate), 20 g / ℓ of _{NaPH 2 O 2 · H 2 O} (sodium hypophosphite monohydrate), 5 g / ℓ of _{C 6 H 5 O 7 Na 3} · H 2 O (sodium Citrate) and a second solution consisting of 10 ml / l HF and a third solution for adjusting and stabilizing the pH, maintaining the temperature below 70 ° C. and maintaining the pH at 6.5, soaking for 5, 10 or 15 minutes. Nickel coating was performed on the surface.

As a result of the nickel coating according to the present embodiment, FIGS. 2 to 4 are enlarged photographs of the electrode catalyst according to the present invention with a scanning electron microscope (SEM), and 5a, 5b, and 5c are EDS for analyzing the composition of materials. It is a graph which performed Energy Dipspersive spectorcopy. In addition, the compositions of points 1, 2, and 3 of FIG. 3 according to FIGS. 5A, 5B, and 5C are shown, and the results are shown in Tables 1, 2, and 3 below.

Table 1

division Ni Mn Zr Co V Ti Sum weight(%) 60.48 16.05 14.75 4.15 3.16 1.42 100 atom(%) 62.59 17.75 9.82 4.28 3.77 1.8 100

TABLE 2

division Ni P Mn V Sum weight(%) 93.18 4.68 1.67 0.47 100 atom(%) 89.27 8.49 1.71 0.52 100

TABLE 3

division Ni P Mn V Ti Sum weight(%) 91.1 6.92 1.48 0.38 0.12 100 atom(%) 85.63 12.33 1.48 0.42 0.14 100

That is, as shown in FIGS. 2 to 4 and Tables 1 to 3, it can be seen that nickel is coated on the surface of the hydrogenation alloy.

The results of operating the fuel cell at the operating temperature of about 35 ° C. with MH1 and MH2 coated with nickel as described above and Japanese Patent Application Laid-open No. 2002-246039 are shown in FIG. 6. As shown in Figure 6, it can be seen that the performance similar to the fuel cell using the fluorinated MH2 catalyst as an electrode.

The fuel cell, the catalyst for the electrode, and the electrode of the fuel cell according to the present invention have an oxidation resistance to the fuel supplied to the anode, thereby providing a stable power supply even when used for a long time.

In addition, the electrode catalyst according to the present invention has an advantage of being able to stably be attached to the catalyst support material when used to attach to the catalyst support material of nickel material to extend the life of the fuel cell.

Claims (13)

A fuel electrode comprising a hydrogen storage alloy coated with nickel; A fuel cell, characterized in that it comprises an anode provided between the fuel electrode and the electrolyte portion. The method of claim 1, The hydrogen storage alloy is a metal hydride (MH) fuel cell, characterized in that. The method of claim 2, The metal hydride is a fuel cell, characterized in that the powder form. The method of claim 2 or 3, The metal hydride is AB ₂ series, A is Zr or Ti is used, B is Ni, V, Mn, Cr, Al is used in the fuel cell. The method of claim 1, The anode is a fuel cell, characterized in that the hydrogen storage alloy coated with nickel. A fuel electrode made of a metal hydride coated with nickel; A fuel cell, characterized in that it comprises an anode provided between the fuel electrode and the electrolyte portion. An electrode of a fuel cell comprising a fuel electrode and an oxide electrode disposed between the fuel electrode and the electrolyte portion, Electrode catalyst consisting of hydrogen storage alloy coated on the surface of nickel. The method of claim 7, wherein The catalyst is an electrode catalyst, characterized in that the powder form. The method of claim 7, wherein The catalyst is an electrode catalyst, characterized in that the fiber form. The method of claim 7, wherein The catalyst for the electrode, characterized in that the catalyst forms a porous body. The method of claim 7, wherein The hydrogen storage alloy is an electrode catalyst, characterized in that the metal hydride. The method of claim 7, wherein The catalyst is an electrode catalyst, characterized in that attached to the catalyst support material of nickel or nickel alloy material. An electrode of a fuel cell made of the catalyst for an electrode according to any one of claims 7 to 8.

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