JPH10154519A - Fuel cell separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell separator in which structure strength design and passage design can be independently conducted, and pressure difference between an anode side and an cathode side can easily be optimized. SOLUTION: A center plate 22 having irregular part 22a and a corrugate plate 24 fitted to the cathode side of the center plate are provided in a reaction portion. The upper and lower faces of the corrugate plate 24 communicate and gas flows its inside, and thereby, a cathode passage is constructed inside the corrugate plate and between the same and the center plate so that pressure loss can be freely set by the thickness of the corrugate plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a separator for a molten carbonate fuel cell.

[0002]

2. Description of the Related Art In a molten carbonate fuel cell (FIG. 3A), a thin flat electrolyte plate (tile) 1 is provided with a fuel electrode (anode).
2 and a single cell 4 sandwiched between flat electrodes of an air electrode (cathode) 3 and a conductive bipolar plate (separator) 5
Consists of Since the voltage of the separator 5 is low (about 0.8 V) in the single cell 1, the separator 5 is used to form a battery in which these are stacked in multiple stages. The stacked batteries are called a stack.

Further, as means for supplying the process gas to each cell in the stack, as shown in FIG. 3B, an external manifold system (a) for directly supplying the process gas from the side of the stack, and a through-hole perpendicular to the separator itself are used. There is an internal manifold system (b) in which a manifold 8 is provided and a process gas is supplied to each cell via the manifold.

The above-described fuel cell separator has a plurality of functions, such as a partition plate for separating anode gas and cathode gas, a current collector for connecting each cell, and a gas manifold for supplying anode gas and cathode gas to each cell. It has heat resistance to withstand high temperatures of about 700 ° C or more, corrosion resistance to withstand highly corrosive molten carbonates,
Due to the electrolyte plate (tile) containing molten carbonate, flatness and flexibility for forming a wet seal between separators, low electric resistance for lowering the internal resistance of the battery, and the like are required.

In order to satisfy these requirements, fuel cell separators have conventionally been manufactured by precision machining. However, in order to reduce power generation costs, a corrugated separator having a flow path portion formed of a corrugated plate, A press-type separator in which each component of the fuel cell separator is formed by press working has already been developed.

In the corrugated separator, a corrugated plate is attached to both sides of a central flat plate to form a flow path.
Although it is easy to increase the size due to its high flatness and flexibility, the cost of processing the corrugated plate and the cost of assembling the separator are high, and there is a problem that mass production is not possible at low cost. On the other hand, in the press-type separator, since both the flow paths are integrally formed by press working, there is a high possibility that the processing cost and the assembly cost can be significantly reduced. For this reason, a press-type separator which can be mass-produced by press working has been proposed and has already been partially implemented (for example, Japanese Patent Application No. 7-217538 by the applicant of the present invention, undisclosed).

As shown in FIGS. 4 and 5, a press-type separator disclosed in Japanese Patent Application No. 7-217538 has three press-formed products (center plate 13, mask plates 11 and 15) and two perforated plates (center plate 13). Collectors 12 and 14), and the structure is such that the periphery of the three press-formed products and the manifold portion are joined and integrated. In FIG. 4, 8
Reference numerals a and 8b denote internal manifolds.

[0008]

FIG. 6 is an enlarged sectional view of a reaction section of the press type separator. As shown in this figure, the center plate 1
Reference numeral 3 functions as a partition plate for separating the anode gas and the cathode gas, and a cathode gas passage and an anode gas passage are formed between the center plate 13 and the collectors 12 and 14, respectively.

In a normal fuel cell operation (power generation) state, the gas flow rates on the anode side and the cathode side of the fuel cell are greatly different, and the cathode side is five to one times the anode side.
A flow rate of 0 times flows. On the other hand, as shown in FIG. 7, the flow path cross-sectional area on the anode side and the cathode side by the center plate 13 is almost the same, or the flow path shape is such that the flow area on the cathode side is slightly larger. I have. For this reason, when the anode gas and the cathode gas are flowed across the cell in the stack in the operation state of the fuel cell, the pressure loss on the cathode side is larger than the pressure loss on the anode side, and a large differential pressure between the anode and the cathode. (Differential pressure between poles)
There was a problem that occurred.

In order to solve this problem, it is conceivable to change the center plate into a cross-sectional shape that is wider on the cathode side and narrower on the anode side, but it is actually very difficult to realize this cross-sectional shape. That is, since the anode side and the cathode side have the same flow path height, it is necessary to increase the support span of the cathode collector in order to increase the flow path on the cathode side. However, increasing the support span requires a correspondingly thicker cathode collector to increase bending stiffness, which not only increases the cost of manufacturing the collector, but also increases the thickness of the cell and the overall height of the stack. The whole stack becomes large and the manufacturing cost increases. In addition, when the support span on the cathode side is increased, the reaction on the anode side at that portion is hindered by the close contact with the center plate, and there is a possibility that the battery performance may be reduced. Further, the fuel cell requires a relatively high surface pressure (for example, 2-3 kg / c) in order to reduce the internal resistance of the cell.
m ² ), the center plate needs to withstand this contact pressure for a long time at the operating temperature of the fuel cell (for example, about 650 ° C. to 700 ° C.).

In order to satisfy these demands, the structural strength of the center plate is carefully designed, and in order to maintain the performance of the fuel cell and to avoid a large increase in cost, the anode side and the cathode must be It is necessary that the flow path cross-sectional area on the side is substantially the same or that the flow path area on the cathode side is slightly larger.

In order to solve this problem without largely changing the cross-sectional shape of the center plate, the inventors of the present invention have proposed a method in which a gas flow direction is set in a current collector plate (collector) constituting a cathode gas flow path. A fuel cell in which a long hole is provided in the fuel cell to constitute a part of the flow path was invented and filed (Japanese Patent Application Laid-Open No. 7-192740). With this fuel cell, the long hole of the current collector plate can be positively utilized as a flow path, and the cathode-side flow path area can be substantially enlarged.

However, since the thickness of the current collector is small (for example, 0.5 to 1.0 mm) with respect to the height of the center plate channel (for example, 3 to 4 mm), the flow path area of the current collector is reduced. There was a problem that the enlargement ratio was at most a little less than twice. Further, if the enlarging rate is increased by further increasing the thickness of the current collector plate, the thickness of the separator is increased and the overall height of the stack is increased, so that the entire stack is increased in size and the manufacturing cost is increased.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a fuel cell separator that can easily optimize the pressure difference between the anode side and the cathode side without significantly increasing the separator thickness and the total stack height. is there. Another object of the present invention is to provide a structural strength design for maintaining the anode and the cathode at an optimum support pitch for maintaining battery performance and determining the flow path shape of the center plate so as to withstand a predetermined surface pressure; It is an object of the present invention to provide a fuel cell separator capable of independently designing the flow path on the cathode side and the cathode side.

[0015]

According to the present invention, there is provided a fuel cell separator comprising a fuel cell having a cathode and an anode mounted on both sides thereof and alternately stacking a plurality of layers with an electrolyte plate interposed therebetween. A center plate having an uneven portion in the reaction portion, and a corrugated plate attached to the cathode side of the center plate, the corrugated plate is configured such that upper and lower surfaces communicate with each other and gas flows inside, As a result, a cathode channel is formed between the inside of the corrugated plate and the center plate,
A fuel cell separator is provided.

With this configuration, the corrugated plate can be designed and manufactured independently, so that the structural strength design of the center plate and the flow path design on the cathode side using the corrugated plate can be performed independently, The electrode-to-pole differential pressure between the cathode side and the cathode side can be easily optimized. In addition, since the unevenness of the center plate can be set to a low height suitable for the anode gas, the thickness of the separator and the overall height of the stack can be sufficiently reduced even if the corrugated plate is used on the cathode side.

Further, by forming the corrugated portion of the center plate into a corrugated shape, it can be easily and accurately formed by press forming.

According to a preferred embodiment of the present invention, the corrugated plate is a plate-like member formed by cutting a thin metal plate and bending the plate, and the upper and lower surfaces are flat and sufficiently small to support the cathode. It has an opening. According to this configuration, a corrugated plate having a required thickness (for example, about 1 to 3 mm) can be freely designed and manufactured using a thin plate material (for example, about 0.1 to 0.3 mm), and while functioning as a current collector. The cathode gas can be caused to flow at a low pressure loss in the corrugate.

Further, according to a preferred embodiment of the present invention, there is provided an anode collector mounted on the opposite side of the center plate from the corrugated plate, and an anode flow path is formed between the anode collector and the center plate. The height of the flow path due to the uneven portion of the plate is set so that the anode flow path can flow the anode gas with a sufficiently low pressure loss. The anode collector is preferably a flat plate having fine holes. With this configuration, the anode can be securely held, the height of the uneven portion of the center plate can be set to a necessary and sufficient height, and the thickness of the separator and the overall height of the stack can be sufficiently reduced.

[0020]

Preferred embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, common portions are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a sectional view of a reaction part of a separator according to the present invention. The fuel cell separator 20 of the present invention is configured such that a cathode 3 and an anode 2 are attached to both surfaces thereof, and a plurality of the fuel cells are alternately stacked with the electrolyte plate 1 interposed therebetween to constitute a fuel cell. Therefore, by sandwiching the electrolyte plate 1 between a large number of separators 20, a large number of cells can be electrically connected in series via the separators 20,
High voltage can be achieved. In this figure, the cathode 3 is attached to the upper surface and the anode 2 is attached to the lower surface, but it may be set upside down.

The separator 20 of the present invention includes a center plate 22 having an uneven portion 22a in a reaction portion, and a corrugated plate 24 attached to the center plate 22 on the cathode side. Further, in the embodiment of FIG. 1, an anode collector 25 is further provided on the opposite side of the center plate 22 from the corrugated plate 24, and an anode flow path is formed between the anode collector 25 and the center plate 22. ing. Anode collector 25
Is preferably a flat plate having small holes small enough to hold the anode 2.

The uneven portion 22a of the center plate 22
As shown in FIG. 1, it is shaped into a waveform. It is preferable that the waveform has a shape in which the cross-sectional area of the flow path on the anode side and the flow path on the cathode side are substantially the same, or the flow path area on the cathode side is slightly larger. The height of the flow path formed by the concave and convex portions 22a of the center plate 22 is set sufficiently small (low) within a range in which the anode flow path allows the anode gas to flow with sufficiently low pressure loss.

With the above configuration, the center plate 2
The uneven portion 2 can be easily and accurately formed by press molding, and the anode can be securely held.
The height of the uneven portion of the center plate can be set to a necessary and sufficient height, and the thickness of the separator and the overall height of the stack can be sufficiently reduced.

FIG. 2 is a perspective view of the corrugated plate and the center plate. As shown in this figure, the corrugated plate 2
Reference numeral 4 denotes a flat plate-like member formed by cutting a thin metal plate with a notch, and has a flat upper and lower surface and a sufficiently small opening so as to support the cathode 3. This metal plate has high conductivity and corrosion resistance, and is about 0.1 to 0.3.
It is good to be a thin plate of about mm.

The thickness of the corrugated plate 24 is set so that when the inside of the corrugated plate 24 and the space between the corrugated plate 24 and the center plate 22 are formed as a cathode flow path, the pressure loss on the cathode side is substantially equal to that on the anode side. It is good to set.

With the above structure, the corrugated plate 24
Can be configured so that the upper and lower surfaces communicate with each other and gas flows through the inside, and the corrugated plate 24 having flat openings and sufficiently small openings to support the cathode 3 is formed by bending. It can be manufactured with high precision and at low cost. In addition, a thin plate material (for example, 0.1 to 0.3 m
m), the corrugated plate 24 having a required thickness (for example, about 1 to 3 mm) can be freely designed and manufactured, and the cathode gas can be flowed into the corrugate at a low pressure loss while functioning as a current collector. it can.

Further, since the corrugated plate 24 can be designed and manufactured independently, the structural strength design of the center plate 22 and the flow path design on the cathode side using the corrugated plate 24 can be performed independently. The electrode-to-pole differential pressure between the cathode side and the cathode side can be easily optimized. In addition, since the uneven portion of the center plate 22 can be set to a low height suitable for the anode gas, the thickness of the separator and the overall height of the stack can be sufficiently reduced even if the corrugated plate 24 is used on the cathode side.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0029]

As described above, the fuel cell separator of the present invention easily optimizes the pressure difference between the anode and the cathode without greatly increasing the thickness of the separator and the overall height of the stack. And a structural strength design that determines the flow path shape of the center plate so that the anode and the cathode can be held at an optimal support pitch that maintains battery performance and that withstands a predetermined surface pressure. It has excellent effects such as that the design of the flow path can be performed independently.

[Brief description of the drawings]

FIG. 1 is a sectional view of a reaction part of a separator according to the present invention.

FIG. 2 is a perspective view of a corrugated plate and a center plate.

FIG. 3 is an explanatory view of a conventional molten carbonate fuel cell.

FIG. 4 is a plan view of a separator according to the prior application.

FIG. 5 is an exploded view of the separator of FIG.

FIG. 6 is a sectional view of a reaction part of the separator of FIG.

[Explanation of symbols]

 Reference Signs List 1 electrolyte plate (tile) 2 fuel electrode (anode) 3 air electrode (cathode) 4 single cell 5 bipolar plate (separator) 8 manifold 8a, 8b internal manifold 10 separator 11 cathode mask 12 cathode collector 13 center plate 14 anode collector 15 anode Mask 20 Fuel cell separator 22 Center plate 22a Irregularities 24 Corrugated plate 25 Anode collector

Claims (5)

[Claims] 1. A fuel cell separator comprising a plurality of fuel cells each having a cathode and an anode mounted on both surfaces thereof and alternately stacking a plurality of electrolyte plates with an electrolyte plate interposed therebetween. And a corrugated plate attached to the cathode side of the center plate. The corrugated plate is configured such that upper and lower surfaces communicate with each other and gas flows through the corrugated plate. A cathode flow path is formed between the fuel cell separator and the fuel cell separator. 2. The corrugated plate is a plate-like member formed by cutting and bending a thin metal plate, and has flat upper and lower surfaces and a sufficiently small opening to support a cathode. The fuel cell separator according to claim 1, wherein 3. An anode collector mounted on the opposite side of the center plate from the corrugated plate, wherein an anode passage is formed between the anode collector and the center plate, and the passage height due to the uneven portion of the center plate is The anode flow path is set so that anode gas can flow with a sufficiently low pressure loss.
Or the fuel cell separator according to 2. 4. The fuel cell separator according to claim 1, wherein the anode collector is a flat plate having a small hole. 5. The fuel cell separator according to claim 1, wherein an uneven portion of the center plate is formed in a corrugated shape.