JPS6331484Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a phosphoric acid electrolyte fuel cell, for example, and is a fuel cell equipped with a protection means in case some of the cells forming a cell stack become deteriorated during operation of the cell. It concerns the structure of the battery.

This type of fuel cell is constructed by stacking a large number of single cells consisting of a fuel electrode, an electrolyte-impregnated matrix, and an air electrode in combination with conductive plates such as bipolar plates or porous electrode substrates with gas passage grooves. It consists of
Here, the conductive plate partitions a gas chamber for supplying a reactive gas to the electrodes of the cell, and
It serves to electrically connect adjacent cells by contacting the electrodes, and is incorrectly made of, for example, a carbon-based material.

In general, the voltage that can be extracted from a single cell is 1V or less, and in order to obtain a practical output voltage, a large number of single cells are stacked to form a cell stack as described above, and each battery is connected via the conductive plate described above. electrically connected in series.

By the way, if even one cell in a group of cells making up a cell stack deteriorates due to lifespan or failure during operation of a fuel cell, not only will the output of the cell stack as a whole decrease, but it will also deteriorate depending on the operating conditions at that time. Eventually, a so-called reversal phenomenon occurs in the deteriorated cell, causing it to deviate from the region where it reacts as a battery and cause electrolysis. In such a situation, oxygen is generated on the fuel electrode side and hydrogen is generated on the air electrode side, resulting in an extremely dangerous situation. Furthermore, there is a risk that the battery components may melt or even be destroyed due to abnormal heat generation. For this reason, in the past, if even one cell deteriorated even though other cells were healthy, operation was immediately stopped and the entire cell stack was replaced or the cell stack was disassembled. I had to replace the deteriorated battery. However, since the operation down time required for this is long, it greatly affects the operating rate of the battery. Note that detection of a deteriorated cell is performed by monitoring the output voltage of the entire cell stack and each cell stack.

This idea was developed in consideration of the above points, and its purpose is to protect the battery from a serious accident by simple operation even if a degraded cell battery occurs in a part of the cell stack during operation. Another object of the present invention is to provide a fuel cell equipped with a means that allows continuous operation without any practical problems.

This invention will be described in detail below based on illustrated embodiments.

The illustrated example is a fuel cell in which a large number of cells 1 are stacked with bipolar plates 2 in between to form a cell stack. Single battery 1
It is constructed by stacking a fuel electrode 12 and an air electrode 13 above and below a matrix 11 impregnated with an electrolyte. The bipolar plate 2 is a carbon-based conductive plate that is alternately stacked with the unit cells 1 and has fuel passage grooves 21 and air passage grooves 22 orthogonal to each other formed on its upper and lower surfaces, as is well known.

By the way, according to this invention, a plurality of screw holes 23 are pre-drilled in the circumferential side of each bipolar plate 2 in a distributed manner. Additionally, a shorting piece 3 for electrically shorting the cell 1 by bridging the bipolar plates 2 together, and a mounting screw 4 for connecting the shorting piece 3 to the bipolar plate 2 are separately prepared. There is. During normal operation of the fuel cell, the short-circuiting piece 3 and screw 4 are removed and stored separately, and when a deteriorated cell occurs in a part of the cell stack, the deteriorated cell shown by reference numeral 1' is held in place. Then, a shorting piece 3 is connected between the bipolar plates 2 that are in contact with each other on both sides through a mounting screw 4, and the deteriorated cell 1' is short-circuited and electrically separated from the cell stack. Therefore, the current flows through the shorting piece 3, and no current flows between the electrodes of the deteriorated cell 1'. In this way, there is no fear of electrolysis occurring due to the reversal phenomenon, and the entire cell stack, with the exception of one cell, can continue to generate electricity. In this case, the number of cells connected in series in the entire cell stack is reduced by one, so the output voltage decreases by that amount.
Since the voltage extracted from each cell is less than 1V,
There is almost no problem in practical driving. Furthermore, screw holes 23 are pre-drilled on the circumferential side of the bipolar plate 2, and the connection of the shorting piece 3 can be completed in a short time with a simple operation.

Although the illustrated example shows a cell stack in which single cells are stacked with bipolar plates in between, instead of this bipolar plate, a porous electrode substrate with reaction gas passage grooves and a separate plate for gas separation can be used. Of course, the present invention can also be applied to batteries in which a cell stack is constructed by stacking unit cells. Further, in this case, a main mounting stage is provided so that the shorting member can be connected to the electrode substrate, which is a conductive plate.

As mentioned above, in this invention, when a deteriorated cell occurs in the cell stack, the conductive plate is equipped with a means for attaching a short-circuiting member that electrically short-circuits only the deteriorated cell. Even if a single battery occurs, the deteriorated single battery can be easily short-circuited between the conductive plates that sandwich the single battery, preventing the malfunction of the single battery from spreading to the entire cell stack, and allowing the cell stack to continue operating. Provides practical benefits that can be maintained.

[Brief description of the drawings]

FIG. 1 is a perspective view of the entire cell stack showing the state in which the shorting pieces are connected according to this invention, and FIG. 2 is an enlarged cross-sectional view of the main parts in FIG. 1. DESCRIPTION OF SYMBOLS 1...Single cell, 2...Bipolar plate as a conductive plate, 3...Short circuit piece, 4...Short circuit piece mounting screw, 11...Matrix, 12...Fuel electrode, 13...Air electrode, 23... ...screw hole.

Claims (1)

[Claims for Utility Model Registration] 1. A cell stack in which a large number of single cells each consisting of a fuel electrode, a matrix, and an air electrode are stacked together via a conductive plate provided with a gas supply passage to each electrode, and a deteriorated single cell is contained in the cell stack. and a short-circuiting member that electrically short-circuits the deteriorated unit cell when the deterioration occurs, wherein the conductive plate has means for attaching the short-circuiting member. 2 Utility Model Registration Scope of Claims In the fuel cell according to claim 1, the means for attaching the short-circuiting member is a short-circuiting member attaching screw and a screw hole for the shorting member attaching screw drilled on the circumferential side of the conductive plate. A fuel cell featuring: