1. Technical Field
The present invention relates to a fuel cell and to a method of manufacturing the fuel cell.
2. Description of the Related Art
In a fuel cell, the output voltage that can be provided by an individual cell may be a fixed value, determined by the electrochemical reactions. As such, in order to supply the operating power required by an electronic product, it may be necessary to use a DC-DC converter or serially connect the individual cells to increase the output voltage.
According to the method of arranging the individual cells for connection, a fuel cell can be divided into a bipolar stack or a monopolar stack.
FIG. 1 is a cross-sectional view of a fuel cell according to the related art, in which a bipolar stack structure is shown. In the case of medium- or large-sized fuel cells, most of the fuel cells take the form of a bipolar stack. As illustrated in the drawing, cells which include anodes 2, 3 and cathodes 2, 4 formed in contact with a membrane 1, and separation plates may be stacked alternately in layers.
The bipolar stack structure may entail a large volume for the fuel cell, and are thus applied more often in medium- to large-sized fuel cells. Since the power supply used in portable electronic equipment may desirably be given a thin shape, it can be problematic to employ a fuel cell of a bipolar stack structure for such a power supply, due to the large thickness involved. As such, there can be problems in implementing a compact size and in providing a high output.
To overcome these problems of the bipolar stack structure, a fuel cell can be implemented to have a monopolar stack structure. The fuel cell of a monopolar stack structure can provide a higher output density per volume, and enables the supply of fuel without external power, so that the form of the fuel cell may be varied relatively freely. As such, the monopolar stack structure is often employed in small-sized fuel cells.
The monopolar stack structure can in turn be divided into a banded structure or a flip-flop structure.
The banded structure may require a connection crossing the membrane, while the flip-flop structure may be of a simple shape, having only a single-layer connection.
While the banded structure may simplify the method of supplying fuel and air, the banded structure may require additional complicated equipment for connecting the electrodes in serial.
With the flip-flop structure, it is possible to naturally form a serially connected stack by having adjacent unit cells share a common electrode. However, the fuel cell thus formed may entail an extremely complicated flow path for supplying the fuel and air.