KR101530787B1 - Fuel cell unit - Google Patents

Abstract

A fuel cell unit may comprise: a membrane electrode assembly; gas diffusing layers arranged on both sides of the membrane electrode assembly; metal separating plates arranged outside of the gas diffusing layers and having multiple channel units and land units; and interval maintaining members maintaining the interval between the metal separating plates and the gas diffusing layers by being inserted into the channel units.

Description

[0001] FUEL CELL UNIT [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fuel cell, and more particularly, to a fuel cell capable of maintaining a gap between a channel portion and a gas diffusion layer of a metal separator.

Generally, a fuel cell includes a plurality of fuel cell units, and the fuel cell units include a membrane electrode assembly (MEA), a gas diffusion layer, and a separator plate.

The separation plate supplies hydrogen and oxygen to each electrode of the membrane electrode assembly, and a flow path for discharging water, which is a byproduct of the electrochemical reaction, is formed. The separator plate mechanically supports the membrane electrode assembly and the gas diffusion layer, and performs an electrical connection function with adjacent unit cells.

In recent years, a metal separator is often used as the separator, and the metal separator includes a channel portion which is a flow passage of fuel and oxidizer, and a land portion which is in contact with the gas diffusion layer and is an electrical passage.

When the fuel cell module is stacked with the membrane electrode assembly, the gas diffusion layer, and the metal separator, the gas diffusion layer is recessed into the channel portion, and a nonuniform flow distribution deviation occurs in the channel, Performance degradation may occur. In addition, a movement path of electrons generated by the electrochemical reaction of the fuel cell is limited to the land portion, which limits the internal resistance of the fuel cell.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell capable of maintaining a gap between a channel portion and a gas diffusion layer of a metal separator.

The fuel cell includes a membrane electrode assembly, gas diffusion layers disposed on both sides of the membrane electrode assembly, a plurality of land portions and a plurality of channel portions disposed on an outer surface of the gas diffusion layers, And spacing members inserted into the channel portions to maintain spacing between the gas diffusion layers and the metal separator plates.

The spacing members may be made of the same material as the metal separator plates.

The spacing members may be one of a coiled metal wire and a metal strip.

The metal separators may include a ferritic stainless steel having a chromium content of 28 wt% or more. Alternatively, the metal separators may comprise austenitic or ferritic stainless steel whose surface is coated with gold.

The thickness of the metal separation plates may be 0.2 mm or less, and preferably the thickness of the metal separation plates may be 0.05 mm to 0.15 mm.

The thickness of the gap retaining members may be 0.2 mm or less, and preferably the thickness of the gap retaining members may be 0.05 mm to 0.1 mm.

The fuel cell as described above can prevent the gas diffusion layer from sinking through the gap holding member inserted into the channel portion of the metal separator. Therefore, the fuel cell cell can reduce the distribution deviation of the reactive gas to the gas diffusion layer.

Since the spacing members contact the metal separator plates and the gas diffusion layers, the fuel cell cell can obtain an electron transfer path increasing effect. As a result, the internal resistance of the fuel cell can be reduced.

1 is a conceptual diagram for explaining a fuel cell according to an embodiment of the present invention.
2 is a cross-sectional view illustrating the fuel cell shown in FIG.
3 is an enlarged view of region A in Fig.
4 is a graph showing a current density performance evaluation result between the fuel cell of FIG. 2 and a conventional fuel cell.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structures are shown enlarged from the actual for the sake of clarity of the present invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, where a section such as a layer, a film, an area, a plate, or the like is referred to as being "on" another section, it includes not only the case where it is "directly on" another part but also the case where there is another part in between. On the contrary, where a section such as a layer, a film, an area, a plate, etc. is referred to as being "under" another section, this includes not only the case where the section is "directly underneath"

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

FIG. 1 is a conceptual view for explaining a fuel cell according to an embodiment of the present invention. FIG. 2 is a sectional view for explaining a fuel cell shown in FIG. 1, and FIG. 3 is an enlarged view And FIG. 4 is a graph showing a current density performance evaluation result between the fuel cell of FIG. 2 and a conventional fuel cell.

Referring to FIGS. 1 to 4, the fuel cell may include a plurality of stacked fuel cell cells 100.

The fuel cell 100 may include a membrane electrode assembly 110, a gas diffusion layer 120, metal separator plates 130, and spacing members 140.

The membrane electrode assembly 110 includes an electrolyte membrane 111, an anode electrode 113 disposed on one side of the electrolyte membrane 111, and a cathode electrode 115 disposed on the other side of the electrolyte membrane 111 can do.

The electrolyte membrane 111 is densely configured to prevent permeation of hydrogen and air as reaction gases. In addition, the electrolyte membrane 111 may be an ion conductive polymer membrane having no electron conductivity, but high oxygen ion conductivity.

One of the anode 113 and the cathode 115 may be an air electrode for generating a reduction reaction of oxygen and the other of the anode 113 and the cathode 115 may be a cathode, It may be an anode. In this embodiment, the anode electrode 113 is a fuel electrode and the cathode electrode 115 is an air electrode.

The anode electrode 113 and the cathode electrode 115 may have a porous structure capable of diffusing the reactive gas, and may include a material having a high electron conductivity. In the anode electrode 113, an oxidation reaction of hydrogen occurs as shown in the following reaction formula 1, and a reduction reaction of oxygen occurs in the cathode electrode 115 as shown in the following reaction formula (2).

[Reaction Scheme 1]

[Reaction Scheme 2]

Accordingly, the reaction in the entire fuel cell 100 is represented by the following reaction formula (3).

[Reaction Scheme 3]

That is, in the anode electrode 113, hydrogen ions and electrons are generated by the oxidation reaction of hydrogen. In the cathode electrode 115, oxygen ions are generated by the reduction reaction of oxygen. The oxygen ions can move to the anode electrode 113 through the electrolyte membrane. The oxygen ions moved to the anode electrode 113 react with the hydrogen ions of the anode electrode 113 to generate water vapor.

Electrons are generated in the anode electrode 113 and electrons are consumed in the cathode electrode 115. When the anode electrode 113 and the cathode electrode 115 are connected to an external circuit, And electrical energy is generated.

The gas diffusion layers 120 may be disposed on both sides of the membrane electrode assembly 110. In addition, the gas diffusion layers 120 can transfer the reactant gas transferred from the metal separator plates 130 to the anode 113 and the cathode 115. The gas diffusion layers 120 may be formed of any conductive material conventionally used. For example, the gas diffusion layers 120 may include one of carbon cloth, carbon paper, and carbon felt.

The metal separator plates 130 may be disposed on the outer surface of the gas diffusion layers 120. The metal separators 130 may block hydrogen and air as a reaction gas from being mixed with each other and may electrically connect the membrane electrode assembly 110. In addition, the metal separator plates 130 support the membrane electrode assembly 110 and the gas diffusion layers 120 to maintain the shape of the fuel cell.

The metal separator plates 130 may form a passage through which the reactive gas moves, diffuse the reactive gas into the membrane electrode assembly 110, and pass through the generated current. For example, the metal separators 130 may include a plurality of land portions 131 which are in close contact with the gas diffusion layers 120 to support the gas diffusion layers 120 and the membrane electrode assembly 110, And a plurality of channel portions 135 which are reaction channels through which the reaction gas flows. The land portions 131 and the channel portions 135 may be alternately arranged.

The land portions 131 may contact with the gas diffusion layers 120 to serve as current paths. That is, the electrons generated in the anode electrode 113 can move to the cathode electrode 115 through the land portions 131 and the external circuit. The channel portions 135 may form a space with the gas diffusion layers 120, and may be a passage through which the reactive gas moves.

The metal separator plates 130 may include a ferritic stainless steel having a chromium content of 28 wt% or more. In addition, the metal separator plates 130 may include one of austenitic and ferritic stainless steel whose surface is coated with gold. The thickness of the metal separation plates 130 may be 0.2 mm or less. Preferably, the thickness of the metal separator plates 130 may be 0.05 mm to 0.15 mm.

The spacing members 140 may have elasticity and metallic conductivity. For example, the spacing members 140 may be either a metal wire of a coil shape or a metal strip. Here, the thickness of the gap holding members 140 may be 2 mm or less. Preferably, the thickness of the spacing members 140 may be 0.05 mm to 0.1 mm.

In addition, under the condition of no external pressure, the outer diameter of the spacing members 140 may be greater than the depth of the channel portions 135. The spacing members 140 may have an elliptical spiral coil shape due to the pressure generated when the fuel cell 100 is manufactured. The spacing members 140 may contact the metal separator plates 130 and the gas diffusion layers 120 and apply pressure to the gas diffusion layers 120. Accordingly, the gap holding members 140 can prevent the gas diffusion layers 120 and the membrane electrode assembly 110 from sinking. As a result, the fuel cell 100 having the gap holding members 140 can reduce a distribution deviation of the reactive gas to the gas diffusion layers 120.

The spacing members 140 may be made of the same material as the metal separators 130. That is, the gap holding members 140 may include a ferritic stainless steel having a chromium content of 28 wt% or more. In addition, the spacing members 140 may comprise one of austenitic and ferritic stainless steel coated with gold.

The spacing members 140 may contact the metal separator plates 130 and the gas diffusion layers 120 to allow movement of electrons generated in the fuel cell 100. Accordingly, the gap holding members 140 contact the gas diffusion layers 120, and the fuel cell 100 can obtain an effect of increasing the movement path of electrons. As a result, the internal resistance of the fuel cell 100 including the gap maintaining members 140 can be reduced.

<Examples>

The fuel cell used in the embodiment includes a membrane electrode assembly, a gas diffusion layer, a metal separator, and a gap retaining member. Here, the metal separator was made of stainless steel having a thickness of 0.15 mm and containing 30 wt% of Cr, and was formed into a shape having a channel depth of 0.5 mm by a stamping process. The spacing member was made of a spiral coil having an outer diameter of 0.7 mm by slitting and cutting a stainless steel having a thickness of 0.1 mm with a width of 0.3 mm and containing 30 wt% of Cr. The gap holding member is inserted into the channel portion of the metal separator, and the point of contact with the channel portion is fixed through spot welding.

As shown in Fig. 4, at the same current density, it can be seen that the voltage of the embodiment is higher than the voltage of the comparative example without the gap holding member. That is, it can be confirmed that the voltage and current density characteristics of the above embodiment are improved as compared with the comparative example.

The foregoing description is intended to illustrate and describe the present invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the foregoing description of the invention is not intended to limit the invention to the precise embodiments disclosed. In addition, the appended claims should be construed to include other embodiments.

100; Fuel cell
110; Membrane electrode assembly
111; Electrolyte layer
113; Anode electrode
115; Cathode electrode
120; Gas diffusion layer
130; Metal membrane
131; Land portion
135; Channel portion
140; The gap-

Claims (9)

A membrane electrode assembly;
Gas diffusion layers disposed on both sides of the membrane electrode assembly;
Metal separators disposed on an outer surface of the gas diffusion layers and having a plurality of land portions and a plurality of channel portions; And
And gap holding members inserted into the channel portions to maintain a gap between the gas diffusion layers and the metal separator plates. The method according to claim 1,
Wherein the spacing members are made of the same material as the metal separator plates. 3. The method of claim 2,
Wherein the spacing members are one of a coiled metal wire and a metal strip. The method of claim 3,
Wherein the metal separators comprise a ferritic stainless steel having a chromium content of 28 wt% or more. The method of claim 3,
Wherein the metal separators comprise an austenitic or ferritic stainless steel whose surface is coated with gold. The method of claim 3,
Wherein the metal separators have a thickness of 0.2 mm or less. The method according to claim 6,
Wherein the metal separators have a thickness of 0.05 mm to 0.15 mm. The method of claim 3,
Wherein the thickness of the spacing members is 0.2 mm or less. 9. The method of claim 8,
Wherein the thickness of the spacing members is 0.05 mm to 0.1 mm.

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