KR100987096B1 - Separator for fuel cell and fuel cell using the same - Google Patents

Abstract

The present invention provides a separator for a fuel cell having a flow channel composed of an acid and a valley, wherein the at least one groove-shaped groove is formed in the acid of the flow path, and a fuel cell using the same. As described above, by forming a groove-shaped groove in the acid portion of the separator flow path, the contact area between the fuel and the electrode is increased while maintaining the overall fuel and product flow characteristics (flow characteristics), thereby increasing material transfer and thereby fuel cell performance. Improvements can be made.

Fuel Cell, Separator, Acid, Goal, Ditch, Contact Area, Mass Transfer

Description

Separator for fuel cell and fuel cell using same {SEPARATOR FOR FUEL CELL AND FUEL CELL USING THE SAME}

The present invention relates to a separator for a fuel cell with improved electrode utilization efficiency and a fuel cell using the same. Specifically, the separator for a fuel cell improves fuel cell performance by smoothly supplying reactants and removing products by improving the separator structure. Plates and a fuel cell using the same.

In general, in the anode of a polymer electrolyte fuel cell, an oxidation reaction of a fuel such as hydrogen or methanol occurs to generate carbon dioxide, electrons, and ions.

The generated ions move to the reduction electrode through the electrolyte membrane and meet with oxygen to cause an electrochemical reaction to generate water, and the generated electrons move through an external circuit to perform electrical work.

The fuel cell using the polymer electrolyte membrane can solve the problems such as the limitation of the capacity of the secondary battery or the inconvenience caused by the charging time because of the advantage that the use time can be increased by supplying only fuel such as hydrogen or methanol.

Based on these advantages, a fuel cell using hydrogen can be used as an automobile power source or a household generator. In addition, in the case of a fuel cell using methanol as a fuel, methanol can be easily stored and transported and used as a battery replacement for portable electronic devices such as mobile phones, PDAs, and notebook PCs.

In order to improve the performance and commercialization of a fuel cell using such a polymer electrolyte membrane, development of a catalyst having high activity and selectivity, development of a polymer membrane having high conductivity while effectively suppressing cross-over of fuel, is necessary. In addition, development of the separator is necessary.

The action of the separator channel is to supply fuel to the electrode smoothly and uniformly, and to smoothly remove products such as water and carbon dioxide.If the transfer of reactants does not occur smoothly from the channel to the electrode, the concentration overpotential increases. The performance of the fuel cell is degraded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell separator plate and a fuel cell using the same, which can increase the material transfer by increasing the contact area between the fuel and the electrode by improving the flow path structure of the separator plate for the fuel cell, thereby increasing the performance of the overall fuel cell. It is.

In one embodiment of the present invention, there is provided a separator for a fuel cell having a flow channel composed of an acid and a valley, and a fuel cell separator having at least one groove-shaped groove formed in an acid of the flow path and a fuel cell using the same.

As in the present invention, by improving the flow path structure by making a groove in the acid portion of the separator flow path, while increasing the contact area between the fuel and the electrode while maintaining the overall fuel flow characteristics (flow characteristics), This can improve performance. Ditch formation as above is to adopt a common flow path skeleton as a primary skeleton (primary structure), but to form a groove or groove in the mountain part of the flow path of the skeleton (secondary structure), so that fine processing and mass production are possible. In this case, the fuel may be evenly dispersed in the separator.

Hereinafter, a separator for a fuel cell and a fuel cell using the same according to an embodiment of the present invention will be described in detail.

1 is a schematic view showing a fuel cell separator 1b having a trench according to a first embodiment of the present invention in comparison with a general separator 1a. 1 is a plan view showing a flow of fuel in a separator for fuel cells.

For reference, although the separator of FIG. 1 is based on a graphite-type serpentine separator, the present invention is not limited to the above-described specific material and the channel-shaped separator, and different flow paths or materials may be used. Of course, it is possible that the present invention is applied to the separation plate.

Referring to FIG. 1, at least one groove having a ditch shape is formed in a flat surface portion of a rib based on a channel structure (primary structure) consisting of a peak and a valley of a general separation plate 1a ( 1b). That is, the separator has a groove-shaped groove (secondary structure) structure formed in a rib of the separator flow path (primary structure).

Forming a trench in the acid in the fuel cell separator can increase the contact area between the fuel and the electrode, thereby increasing the mass transfer rate of the fuel and the reaction product.

The primary flow path of the separator plate has a shape of sepentine, interdigitated, island, parallel, or the like. In order to manufacture the separator as described above, a method such as mechanical machining, injection or molding, stamping, and etching may be used.

It is preferable that the width of the acid in the separator flow channel having the primary structure is 0.3 to 3.0 mm, the width of the valley is preferably 0.3 to 3.0 mm, and the depth of the valley is preferably 0.1 to 2.0 mm.

The material of the separator is preferably graphite, metal, composite graphite, ceramic, and a material having a corrosion resistant coating formed on these materials.

The secondary structure may be modified in various ways. That is, the secondary structure can be variously modified by changing the shape of the trench for the mountain, the position of the trench for the mountain, the depth of the trench for the mountain, the direction of the trench for the mountain, or the direction of the trench for the flow path direction. Therefore, the contact area between the fuel and the electrode can be adjusted differently.

For example, the individual grooves may be rectangular, square, triangular, trapezoidal or semicircular with respect to the projection surface of the mountain (the plane viewed from above, that is, the plane) of the separation channel.

2 to 6 are schematic diagrams illustrating various groove shapes in embodiments of the present invention.

2 to 6, in the case of the separating plate of FIG. 1, the trench is formed at right angles, but the position of the trench may be modified (FIG. 2), or the depth of the trench may be modified (FIG. 3). Orientation can also be variously modified (Figs. 4 to 6).

In the secondary structure as above, the length of the trench should not interfere with the opposite flow path. That is, adjacent flow paths should not penetrate each other. The distance between the trench and the trench is not limited, and the width of the trench should be within 200% of the width of the valley, and the depth of the trench should be within 100% of the depth of the valley.

As a method for forming the secondary structure as described above, the above-described methods such as machining, injection or molding, stamping, and etching may be used. As one example, etching methods include ion etching, plasma etching, and chemical etching. FIG. 7 shows an example of an ion etching apparatus for forming the shape of a ditch, for example, in a fourth embodiment of the present invention (separator of FIG. 4).

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention in comparison with comparative examples. The following examples are intended to facilitate the implementation of the invention to those of ordinary skill in the art, while at the same time complete the disclosure of the present invention, the present invention is not limited to the following examples and appended claims Various forms of embodiments may be implemented within the scope.

<Comparative Example 1: Curved Separating Plate having a Graphite Material; See FIG. 1A>

A curvature separator (impregnated plate with a width of 1.0 mm, a bone width of 1.0 mm and a bone depth of 1.0 mm) of impregnated graphite material is applied to a direct methanol fuel cell. Cell experiments were conducted.

<Example 1: forming a uniform groove through etching on the curved type plate having a graphite material; See FIG. 1b>

Ditches having a width of 0.1 mm, a length of 0.2 mm (length penetrated perpendicularly from the bone to the mountain), and a depth of 0.1 mm were formed at intervals of 1.0 mm through etching in the mountains of the separator flow channel used in Comparative Example 1. Experimental evaluation of unit cell performance was carried out by applying a grooved separator to a direct methanol fuel cell.

<Example 2: forming a uniform groove through etching on the curved type partition plate having a graphite material, but changing the position of the groove; See Figure 2>

The separation plate having the same conditions as in Example 1 was formed, but the location of the trench was formed by the zigzag method, and applied to the direct methanol fuel cell to evaluate the unit cell performance.

<Example 3: A uniform groove is formed on the curved partition plate having a graphite material by etching, but the depth of the groove is deformed; See Figure 3>

In the separator having the same condition as Example 1, the depth of the trench was formed to be 0.5 mm, and the unit cell performance evaluation experiment was performed by applying to a direct methanol fuel cell.

Example 4 Forming Diagonal Uniform Ditch in the Depth Direction through Etching on the Curved Separator Having a Graphite Material; See Figure 4>

An oblique groove was formed on the separator having the same conditions as in Example 1, and the unit cell performance evaluation experiment was performed by applying to a direct methanol fuel cell.

The experiment for comparing the performance of the unit cell was performed as follows.

Experimental Example: Comparison of Differences in Voltage and Power with Constant Current Changes

Five cells were fastened using each separator to compare the performance of each of the separators of the Examples and Comparative Examples. The operating conditions of the unit cell of the direct methanol fuel cell were the same, 1M methanol was supplied to the anode at 5 cc / min, and 1250 sccm of humidified air was supplied to the cathode. The difference between voltage and power was observed as the current changed.

8 is a graph showing the current-voltage characteristic curves in the case of Examples and Comparative Examples.

As shown in FIG. 8, it can be seen that the performance of the ditched embodiments is generally higher than that of Comparative Example 1 in which the ditch is not formed in the mountain. Therefore, it was confirmed that the separator structure having a higher contact area of the fuel due to the ditch than the conventional separator having a low contact area of the fuel of Comparative Example 1 has high performance due to smooth material transfer.

1 is a schematic view showing a fuel cell separator 1b having a trench according to a first embodiment of the present invention in comparison with a general separator 1a.

FIG. 2 is a schematic view showing a fuel cell separator having a trench according to a second embodiment of the present invention, the position of the trench being changed in the separator of FIG.

FIG. 3 is a schematic view showing a fuel cell separator having a trench according to a third embodiment of the present invention, the depth of the trench being changed in the separator of FIG. 1B.

4 is a schematic view showing a fuel cell separator having a trench according to a fourth embodiment of the present invention, in which the direction of the trench is modified from a straight line to a diagonal line in a depth direction of the separator of FIG. 1B.

FIG. 5 is a schematic view illustrating a fuel cell separator having a trench according to a fifth embodiment of the present invention, in which the trench is modified in a diagonal direction such as a flow path in the separator of FIG.

FIG. 6 is a schematic view illustrating a fuel cell separator having a trench according to a sixth embodiment of the present invention, in which the trench is modified in a direction opposite to the flow of the flow path in the separator of FIG.

7 is a schematic diagram showing an example of an etching apparatus for forming the shape of a trench in embodiments of the present invention.

8 is a graph showing a current-voltage characteristic curve in the case of the examples and comparative examples of the present invention.

Claims (9)

As a separator of a fuel cell in which a flow path skeleton structure composed of an acid portion and a valley portion exists on a separator plate, A plurality of groove-shaped grooves are formed on both side surfaces of the acid portion of the flow path, and the groove-shaped groove is formed so as not to penetrate the acid portion. The method of claim 1, The groove-shaped grooves formed on both side surfaces of the channel portion of the flow path are formed such that the depth direction of the groove is oblique to the vertical height direction of the mountain. The method of claim 1, The groove-shaped groove has a width of 200% or less of the width of the valley, and the groove-shaped groove has a depth of 100% or less of the depth of the valley. The method of claim 1, The contact area between the fuel and the electrode is adjusted by changing the shape of the trench, the position of the trench, the depth of the trench, or the direction of the trench. The method of claim 1, The flow path of the separation plate is any one of a serpentine, interdigitated, parallel (parallel) or island shape (island) or a mixture of these, characterized in that the fuel cell separator. The method of claim 1, The shape of the trench is a fuel cell separator, characterized in that the rectangular, square, triangular, trapezoidal or semi-circular shape based on the plane of the acid. The method of claim 1, The separator is a separator for fuel cells, characterized in that the graphite, synthetic graphite, or a corrosion-resistant coating is performed on them. A unit cell of a fuel cell, comprising the fuel cell separator according to any one of claims 1 to 7. A fuel cell stack comprising a separator for fuel cells according to any one of claims 1 to 7.

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