Fuel cell separator, fuel cell and fuel cell battery

Abstract

Fuel cell separator (10), comprising: a power generation section (10A, 10B) arranged in a central region on a surface of the plate-shaped separator; and a plurality of collector tubes (11A, 11B, 12A and 12B) arranged in a region closer to the edge region than the power generation section (10A, 10B); characterized by reinforcement sections (14A) extending from a gap region (13) formed between the power generation section (10A, 10B) and the collector tubes (11A, 11B, 12A and 12B) to a central region of collector tube rod sections (15) formed between the collector tubes (11A, 11B, 12A and 12B).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a fuel cell separator, a fuel cell and a fuel cell battery. 2. State of the art A fuel cell battery with a membrane electrode assembly (MEA), formed by creating catalyst layers for the electrodes on both sides of an electrolyte membrane and a separator for compressing the MEA, has been proposed and is in practical use. In the fuel cell system with this fuel cell battery, fuel gas is supplied to one of the electrodes (the anode electrode) that form the MEA of the fuel cell battery, and oxidation gas is supplied to the other electrode (the cathode electrode) to cause an electrochemical reaction, thereby generating electricity. Currently, a technique for generating high electrical power is used by forming a stack by stacking multiple cells, each with a single MEA. The separator forming the fuel cell battery is a plate-shaped element with a gas flow path formed on one side opposite the MEA and a manifold used to circulate reaction gas (fuel gas or oxidizer gas) from outside to the gas flow path. The separator serves to prevent short circuits through contact between the anode and cathode electrodes of adjacent fuel cells when stacked fuel cells are separated and to ensure that adjacent cells are electrically continuous. A technique is currently being proposed for arranging multiple protrusion sections in a region between a power generation section formed in a central region of the separator and manifolds formed in a region near the edge (see, for example, JP 2012-018 883 A).Another fuel cell stack with an anode-side separator arranged between a plurality of membrane electrodes is known from DE 11 2014 005 214 T5. The anode-side separator has a separator center area arranged such that it faces a power generation area of ​​the membrane electrode arrangement; an outer circumferential area extending from the separator center area to the outer circumference and having a plurality of openings for coolant supply manifolds; and a rib formed by a rod section, designed to separate adjacent openings for the coolant supply manifolds from one another, over an area between the openings for the coolant supply manifolds and the separator center area. SUMMARY OF THE INVENTION In the separator, the strength of the manifold sections (especially the manifold rod sections that form the manifolds) is low compared to the strength of the power generation section. Therefore, the separator manifold sections deform in the stacking direction when the cells are stacked, causing a problematic decrease or deterioration in sealing performance. In this regard, the use of the technique disclosed in JP 2012-018 883 A likely strengthens the area between the power generation section and the manifolds. However, this technique is not suitable for preventing the deformation of the manifold rod sections, so the problem of decreased sealing performance persists. The present invention was developed starting from the aforementioned problem. It is therefore an object of the present invention to avoid the deterioration of the sealing performance by preventing the deformation of the manifold sections of a fuel cell separator. To solve this problem, the present invention was made. According to one aspect of the present invention, a fuel cell separator is proposed comprising: a power generation section arranged in a central region on a surface of the plate-shaped separator; and a plurality of collector tubes arranged in a region closer to the edge than the power generation section. The fuel cell separator further comprises reinforcement sections extending from a gap region formed between the power generation section and the collector tubes to a central region of collector tube rod sections formed between the collector tubes. In the aforementioned configuration, the reinforcement section is designed to extend from the manifold section formed between the majority of manifolds to the gap area formed between the power generation section and the manifolds, thereby suppressing deformation of the manifold section in the stacking direction and thus preventing a decrease in sealing performance. In the fuel cell separator of the present invention, it is possible to use a projection as the reinforcement section, which projects into a surface in which a cooling water flow path is formed. In this case, the projection can have a flat shape in order to guide cooling water from a cooling water inlet-side manifold to the cooling water flow path, and / or from the cooling water flow path to a cooling water outlet-side manifold. In the above configuration, the reinforcement section (the projection extending into the surface in which the cooling water flow path is formed) can act as a cooling water guide unit to direct cooling water from the cooling water inlet-side manifold to the cooling water flow path, and / or from the cooling water flow path to the cooling water outlet-side manifold. The fuel cell separator of the present invention can be a press-molded separator arranged opposite an anode side of a membrane electrode arrangement, wherein no recessed section is formed in an area that is in contact with the membrane electrode arrangement. This configuration makes it possible to suppress deformation of the manifold section of the press-molded separator, which is located on the anode side, in the stacking direction. Furthermore, the press-molded separator does not have a recessed section in the area in contact with the membrane electrode assembly, thus preventing damage caused by the membrane electrode assembly penetrating the recessed section when in contact with the separator. The fuel cell separator of the present invention can be a flat separator arranged opposite a cathode side of a membrane electrode arrangement. This configuration makes it possible to suppress the deformation of the collector tube section of the flat separator in the stacking direction, which is located on the cathode side. Furthermore, a fuel cell according to the present invention has the aforementioned fuel cell separator. A fuel cell battery according to the invention also has a plurality of the aforementioned fuel cells in a stacked state. According to the present invention, the deformation of the manifold sections of a fuel cell separator can be prevented, thereby avoiding the deterioration of the sealing performance. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 shows a side view of the schematic structure of a fuel cell battery according to an embodiment of the present invention; Fig. 2 shows a view of a surface on the side of a fuel gas flow path of an anode-side separator forming a fuel cell according to an embodiment of the present invention; Fig. 3 shows a view of a surface on the side of a cooling water flow path of the anode-side separator forming the fuel cell according to an embodiment of the present invention; Fig. 4 shows an enlarged view of section IV from Fig. 3; Fig. 5 shows a top view of a cathode-side separator forming the fuel cell according to an embodiment of the present invention; Fig. 6A shows an enlarged top view of an area in the vicinity of a manifold section of a conventional separator; and Fig. 6B shows a sectional view along a line BB in Fig. 6A. DESCRIPTION OF PREFERRED EXECUTION FORMS The following describes embodiments of the present invention with reference to the accompanying drawing. Positional relationships such as top and bottom, right and left, or the like in the drawings are based, unless otherwise indicated, on the positional relationships shown in the drawing. Furthermore, the dimensional relationships in the drawings are not limited to those depicted. Moreover, the embodiments described below are only examples and are not intended to limit the present invention to these embodiments. Rather, the invention can be modified in various ways without deviating from the scope of the invention. First, the construction of a fuel cell battery 1 according to an embodiment of the present invention is described with reference to Fig. 1. The fuel cell battery 1 according to this embodiment comprises a fuel cell stack 3 formed by sequentially stacking a plurality of fuel cells 2. The fuel cell stack 3 is sandwiched between a pair of end plates 4 at both ends and is secured by a load applied in the stacking direction by arranging a retaining element consisting of tension plates 5 to connect the end plates 4 to one another. Although the fuel cell battery 1, consisting of the fuel cells 2 and the like, can be used as a vehicle-based power generation system, for example in a fuel cell hybrid vehicle (FCHV), the fuel cell battery 1 is not limited to this and can also be used as a power generation system mounted on a body that can move independently, such as various mobile bodies (such as a ship, an aircraft or the like) or a robot, or can be used as a stationary fuel cell battery. Fuel cell 2 has a membrane electrode assembly (MEA), not shown, a pair of separators (an anode-side separator 10 and a cathode-side separator 20, which will be described in detail later) for clamping the MEA, a sealing element arranged between the pair of separators, and a seal arranged between the fuel cells. The MEA and the pair of separators consist of a substantially rectangular plate. The MEA is designed such that its outer dimensions are smaller than the outer dimensions of the pair of separators. The MEA has a polyelectrolyte membrane (hereinafter referred to in some cases as the "electrolyte membrane") consisting of an ion-exchange membrane made of a polymer material, and a pair of electrodes (an anode-side diffusion electrode and a cathode-side diffusion electrode) that sandwich the electrolyte membrane from both sides. The electrolyte membrane is larger than each electrode. Each electrode is bonded to the electrolyte membrane, for example, by a hot-pressing process. Each of the electrodes forming the MEA is made, for example, of a porous carbon material (diffusion layer) that carries a catalyst, such as platinum, deposited on one surface of the electrode. One electrode (the anode) is supplied with fuel gas, for example, hydrogen gas, while the other electrode (the cathode) is supplied with oxidation gas, for example, air.These two types of reaction gases cause an electrochemical reaction in the MEA to generate an electromotive force in the fuel cells 2. The sealing element is located between the pair of separators and in the edge section or border region of the MEA. The MEA and the pair of separators, or similar components, are connected to each other by the sealing element. The sealing element can be, for example, an adhesive or similar material that enables chemical bonding with an adjacent element. The seal prevents the escape of oxidation gas, hydrogen gas, or similar gases by sealing between the fuel cells. The seal material can be an elastic body for sealing fluids by physical adhesion to an adjacent element, an adhesive for bonding by chemical bonding with an adjacent element, or similar. Below, a pair of separators (an anode-side separator 10 and a cathode-side separator 20) which form the fuel cell 2 according to the embodiment of the present invention are described with reference to Fig. 2, Fig. 3, Fig. 4 to Fig. 5. The anode-side separator 10 (Fig. 2, Fig. 3 to Fig. 4) and the cathode-side separator 20 (Fig. 5) consist of a gas-impermeable conductive material. This conductive material can be, for example, carbon, a solid resin with electrical conductivity, or a metal such as aluminum, stainless steel, or the like. The base material of separators 10 and 20 in this embodiment consists of a sheet-shaped metal. A membrane with excellent corrosion resistance (for example, a membrane coated with gold) is formed on the surface of each electrode side of the base material. The anode-side separator 10 is arranged such that it faces the anode side of the MEA. The anode-side separator 10 is a so-called press-molded separator, in which a plurality of groove-shaped flow paths are formed by pressing dies on both sides of the anode-side separator 10. More precisely, a fuel gas flow path 11, as shown in Fig. 2, is formed in a central section 10A of the surface (inner surface) that faces the MEA of the anode-side separator 10, while a cooling water flow path 12, as shown in Fig. 3, is formed in a central section 10B of the rear side (outer surface) of the anode-side separator 10. The central sections 10A and 10B of the anode-side separator 10 function as current-generating sections. The MEA has an area that is slightly larger than the area of ​​the central section 10A (power generation section) of the anode-side separator 10.In this embodiment, no recessed section is provided in a region (a region slightly larger than the current generation section 10A) 10C which is in contact with the MEA of the anode-side separator 10, as shown in Fig. 2. In the area located closer to the edge than to the central areas or sections 10A or 10B (power generation section) of the anode-side separator 10, a plurality of collecting tubes (fuel gas inlet-side collecting tube 11A, fuel gas outlet-side collecting tube 11B, cooling water inlet-side collecting tube 12A, and cooling water outlet-side collecting tube 12B) are formed, as shown in Figures 2 and 3. The collecting tubes 11A, 11B, 12A, and 12B of this embodiment are essentially rectangular openings when viewed from above. Fuel gas supplied from the outside is introduced into the fuel gas flow path 11 (see Figure 2) through the fuel gas inlet-side collecting tube 11A and circulates within the fuel gas flow path 11. The fuel gas is then discharged to the outside through the fuel gas outlet-side collecting tube 11B. On the other hand, cooling water supplied from the outside is fed into the cooling water flow path 12 through the cooling water inlet-side manifold 12A (see Fig.3) is introduced and circulates in the cooling water flow path 12. Subsequently, the cooling water is discharged to the outside through the cooling water outlet-side collector pipe 12B. A plurality of projections 14 are provided in a gap region or gap section 13, which is formed between the central region 10A or 10B (power generation region) of the anode-side separator 10 and the plurality of manifolds 11A, 11B, 12A and 12B, wherein the projections 14 are designed to project towards the surface (see Fig. 3) into which the cooling water flow path 12 is formed. As shown in Fig. 4, some (specific projections 14A) of the projections 14 are designed to extend from the gap region 13 to manifold rod sections 15, which are formed between the plurality of manifolds 11A, 11B, 12A and 12B, in order to act as reinforcing sections to suppress deformation of the manifold section. As shown in Fig. 6A, conventionally, projections (reinforcing sections) 140 were formed only in a gap region 13 located between the power generation section of the anode-side separator 10 and the manifolds. Therefore, stacking the fuel cells 2 by means of a seal 30 causes a problematic deformation of each manifold section 15, as indicated by the dashed lines in Fig. 6. In the present embodiment, however, the specific projections 14A (reinforcing sections) are designed such that they extend from the gap region 13 to the central region of the respective manifold sections 15, as shown in Fig. 4, thereby preventing deformation of the manifold sections 15 during cell stacking. Furthermore, each projection 14 of this embodiment has a configuration for guiding cooling water, as shown in Figs. 3 and 4. In particular, the projections 14 are arranged inclined at a predetermined angle relative to the longitudinal direction of the anode-side separator 10 in order to guide the cooling water from the cooling water inlet-side collector tubes 12A on the upper left side of the paper in Fig. 3 to the cooling water flow path 12 on the side of the paper surface located slightly to the right and below compared to the cooling water inlet-side collector tubes 12A, and furthermore to guide the cooling water from the cooling water flow path 12 to the cooling water outlet-side collector tubes 12B on a side of the paper surface located further to the right and below than the cooling water flow path.The specific projection 14A has such a flat shape that the projection inclined at the aforementioned angle is connected to a section that runs along the direction of travel of the collector pipe section 15, as shown in Fig. 4. The cathode-side separator 20 shown in Fig. 5 is arranged such that it faces the cathode side of the MEA. The cathode-side separator 20 is a so-called flat separator, which is designed as an essentially flat plate with no groove on its surface facing the MEA. Furthermore, the flat separator is not only a separator whose surface is not press-molded, but can also be a separator whose surface is less press-molded than that of a press-molded separator. Here, the term "less press-molded" refers to a condition in which a narrower area is press-molded than in a press-molded separator, an area is weakly press-molded, only a few areas are press-molded, or the like. In the area closer to the outer edge than to the central region 21 (current generation section) of the cathode-side separator 20, a plurality of collecting tubes 22 are formed, as shown in Fig. 5. Furthermore, a plurality of projection sections 21A, each circular in plan view, are provided in the vicinity of an edge section of the central region 21 (current generation section) of the cathode-side separator 20. The projection section 21A acts as a reinforcing section that suppresses deformation (bending or waviness) of the cathode-side separator 20. The shape and size of the projection section 21A can be selected from various forms, taking into account the size of the cathode-side separator 20 or the gas flow distribution performance. In the anode-side separator 10 according to the embodiment described above, the specific projections 14A (reinforcing sections) are arranged such that they extend from the manifold sections 15, which are formed between the plurality of manifolds, to the gap area 13, which is formed between the power generation section and the manifolds. This makes it possible to suppress the deformation of the manifold sections 15 in the stacking direction, thereby preventing a decrease in sealing performance. Furthermore, in the anode-side separator 10 according to the embodiment described above, it is also possible that the specific projections 14A (reinforcing sections) and the other projections 14 function as a cooling water guide unit, which guides the cooling water from the cooling water inlet-side collector pipe 12A to the cooling water flow path 12 and from the cooling water flow path 12 to the cooling water outlet-side collector pipe 12B. In the anode-side separator 10 designed as described above according to the embodiment, no recessed section is formed in the area 10C (see Fig. 2) that is in contact with the MEA, thereby preventing the occurrence of damage caused by the MEA that is in contact with the anode-side separator 10 and engages in the recessed section. Although this embodiment describes by way of example that the reinforcing sections 14A (specific sections) extend from the manifold sections 15 of the anode-side separator 10 to the gap area 13, it is also possible to provide reinforcing sections 24 extending from the manifold sections 25 of the cathode-side separator 20 to a gap area 23, as shown by the dashed lines in Fig. 5. This can suppress the deformation of the manifold sections 25 of the cathode-side separator 20 in the stacking direction. The present invention is not limited to the embodiments described above and suitable modifications can be made by the person skilled in the art to these exemplary embodiments which also fall within the scope of the present invention as defined by the claims below. REFERENCE MARK LIST 1 Fuel cell battery 2 Fuel cell 10 Anode-side separator (press-molded separator) 10A, 10B Middle section (power generation section) 10C Section in contact with the membrane electrode assembly 11A, 11B, 12A and 12B Manifold 12 Cooling water flow path 13 Gap section 14 Specific projection (reinforcement section) 15 Manifold bar section 20 Cathode-side separator (flat separator) 21 Middle section (power generation section) 22 Manifold 23 Gap section 24 Reinforcement section 25 Manifold bar section

Claims

Fuel cell separator (10), comprising: a power generation section (10A, 10B) arranged in a central region on a surface of the plate-shaped separator; and a plurality of collector tubes (11A, 11B, 12A and 12B) arranged in a region closer to the edge region than the power generation section (10A, 10B); characterized by reinforcement sections (14A) extending from a gap region (13) formed between the power generation section (10A, 10B) and the collector tubes (11A, 11B, 12A and 12B) to a central region of collector tube rod sections (15) formed between the collector tubes (11A, 11B, 12A and 12B). Fuel cell separator (10) according to claim 1, wherein: the reinforcement section (14A) is a projection that extends into a surface in which a cooling water flow path (12) is formed; and the projection has a flat shape to direct cooling water from a cooling water inlet-side collector pipe (12A) to the cooling water flow path (12), and / or from the cooling water flow path (12) to a cooling water outlet-side collector pipe (12B). Fuel cell separator (10) according to claim 1 or 2, wherein: the separator (10) is a press-molded separator (10) which is arranged opposite an anode side of a membrane electrode arrangement; and no recessed section is formed in an area which is in contact with the membrane electrode arrangement. Fuel cell separator (10) according to claim 1 or 2, wherein the separator (10) is a flat separator (10) arranged opposite a cathode side of a membrane electrode arrangement. Fuel cell (2) comprising a fuel cell separator (10) according to any one of claims 1 to 4. Fuel cell battery (1) comprising a plurality of stacked fuel cells (2) according to claim 5 .

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