TWI779539B - Fuel cell and fuel cell module - Google Patents

Abstract

The fuel cell (1, 26, 28) has a power generation element part and a protection element part. The power generation element part is formed by laminating an electrolyte film (5a) and one or more layers of conductive films (4a, 6a), and is carried out by supplying fuel gas (18, 36, 37) and air (19, 38, 39). generate electricity. The protective element part is formed with a protective film, and only one of fuel gas (18, 36, 37) or air (19, 38, 39) is supplied. The compressive strength of the protective element portion is lower than that of the power generating element portion.

Description

Fuel cell and fuel cell module

The invention relates to a fuel cell cell and a fuel cell module.

In Patent Document 1, it is described that in a fuel cell system, the pressure difference between the fuel electrode and the air electrode is reduced to suppress deterioration of the electrolyte membrane.

In Patent Document 2, it is described that anisotropic etching is performed on a single crystal silicon substrate having a (110) plane as the surface, so that the opening angle between the cross section of the opening of the laminated battery element and the substrate surface is almost 90°. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-183033 [Patent Document 2] Japanese Patent Laid-Open No. 2004-288382

[Problem to be Solved by the Invention]

However, in the prior art, there is a technical problem that the power generating element may be damaged when the pressure difference between the fuel gas and the oxidant gas fluctuates rapidly or increases excessively.

The technique of Patent Document 1 is to provide a pressure adjusting device corresponding to the pressure difference between the fuel gas and the oxidant gas, but it is difficult to respond to instantaneous pressure fluctuations. In addition, this pressure adjustment device is based on the gas pressure difference between the multiple fuel cell stacks, and it is difficult to respond to the pressure difference in the single fuel cell stack.

Even in the technology of Patent Document 2, since the areas of the respective electrolyte membranes are the same, there is a possibility that any single cell in the substrate may be damaged. In addition, when the single cell is broken, hydrogen and oxygen are mixed, which is not preferable.

The present invention has been made in view of the foregoing problems, and aims to provide protection against power generation even when the pressure difference between the fuel gas and the oxidant gas fluctuates sharply or increases excessively by providing a protective element in the fuel cell cell. Damaged fuel cell cells and fuel cell modules in the component part. [Means for solving problems]

Regarding an example of the fuel cell of the present invention, Equipped with: Electrolyte membrane, one or more layers of conductive film are laminated and formed, and the power generation element part is supplied with fuel gas and oxidant gas to generate power, A protective film is formed and only one of the aforementioned fuel gas or the aforementioned oxidant gas is supplied to the protective element portion; The compressive strength of the protective element portion is lower than that of the power generating element portion.

In addition, regarding an example of the fuel cell module of the present invention, having the aforementioned fuel cell, and A separator arranged in the fuel cell to separate the fuel gas and the oxidant gas. [Effect of Invention]

According to the fuel cell according to the present invention, even when there is a sudden pressure change in the supply of fuel gas and oxidant gas, the influence on the power generation element can be reduced, and damage to the fuel cell system can be prevented.

Other subjects, novel features, configurations, and effects can be found in detail from the description of this specification and the accompanying drawings.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The examples are merely examples for explaining the present invention, and omissions and simplifications are appropriately made for clarity of description. The present invention can also be implemented in other various forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not show the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

When there are a plurality of components having the same or equivalent function, the same symbol may be described with different subscripts. In addition, when it is not necessary to distinguish these plural constituent elements, the subscript may be omitted for description.

The invention relates to a fuel cell cell and a fuel cell module. In recent years, fuel cells have attracted attention as a clean energy source that can perform high-energy conversion without emitting pollutants such as carbon dioxide or nitrogen oxides. Among the fuel cells, a solid oxide fuel cell (Solid Oxide Fuel Cell, hereinafter abbreviated as SOFC) as an example has high power generation efficiency and can use easily handled gases such as hydrogen, methane, and carbon monoxide as fuel. Thus, SOFC has many advantages compared with other types of fuel cells, and is expected as a thermoelectric cogeneration system excellent in energy saving and environmental performance.

SOFC has a structure in which a solid electrolyte is sandwiched between a fuel electrode and an air electrode. The electrolyte serves as a partition, and a fuel gas such as hydrogen is supplied to the fuel electrode, and an oxidizing gas such as air is supplied to the air electrode.

Hereinafter, air is used as a representative oxidizing gas, but a gas other than air may also be used as the oxidizing gas.

＜Implementation Type 1＞ FIG. 1 is a plan view of a fuel cell 1 according to Embodiment 1 of the present invention. Fig. 2 is a sectional view along line A-A of Fig. 1 . For the convenience of description, the up-down direction on the paper in FIG. 2 is taken as the up-down direction of the fuel cell 1 , but this direction has nothing to do with the direction in which the fuel cell is actually installed or used.

In addition, in the drawings, in order to make it easier to understand, the parts that are not cross-sectional are sometimes shown with hatching.

The fuel cell 1 has the following configuration. - Semiconductor substrate 2 (substrate) made of single crystal silicon (Si) - The first insulating film 3 formed on the semiconductor substrate 2 - The power generating element part and the protective element part formed on the first insulating film 3

The configuration of the power generating element unit may be a known configuration, and an example will be described below. The power generation element part is formed by laminating an electrolyte membrane and one or more conductive membranes. In this embodiment, the electrolyte membrane is the electrolyte membrane 5a, and the conductive membrane is the first electrode 4a and the second electrode 6a. In the power generating element portion, a first electrode 4 a , an electrolyte film 5 a , and a second electrode 6 a are sequentially laminated on the first insulating film 3 .

In this embodiment, two fuel cell cells 1 are equipped with two protective element parts. A protective film is formed on the protective element portion. In this embodiment, the protective film is formed by laminating the first electrodes 4b, 4c, the electrolyte membranes 5b, 5c, and the second electrodes 6b, 6c.

The power generating element portion and the protection element portion are formed on the same semiconductor substrate 2 . According to such a configuration, the manufacturing steps are simplified.

The semiconductor substrate 2 has a plurality of openings, and the power generating element and the protection element are formed in the openings. The plurality of openings include the first opening 7 and the second openings 8a, 8b. These openings, which cannot be seen from above, are indicated by dotted lines in the plan view of FIG. 1 .

The power generating element portion is formed across a plurality of first openings 7 . At least one (both in this embodiment) of the conductive film (the first electrode 4 a and the second electrode 6 a in this embodiment) is continuous across the plurality of first openings 7 . According to such a configuration, the steps of forming the conductive film are simplified.

In addition, as shown in FIG. 2 as a modified example, one of the conductive films (the first electrode 4a and the second electrode 6a in this modified example) (the first electrode 6a in this modified example) of the power generating element portion may be 4a) is configured so as to be continuous with the conductive film (the first electrode 4c in this modified example) of the protective element portion. According to such a modified example, the steps of forming the conductive film are simplified.

Two protective element parts are respectively formed in the 2nd opening part 8a and the 2nd opening part 8b.

The power generating element unit is supplied with fuel gas and air to generate power. At this time, one of the first electrode 4 a and the second electrode 6 a serves as an anode electrode, and the other serves as a cathode electrode, and each is connected to the outside to supply power to the outside. In addition, the first electrode 4b and the second electrode 6b of the protection element part may be connected to the outside, and the capacitance or resistance value between the first electrode 4b and the second electrode 6b may be measured. The same applies to the first electrode 4c and the second electrode 6c.

The shape and size of the first opening 7 can be designed arbitrarily, for example, it is rectangular in planar view (direction of FIG. 1 ), and the length of one side is about 5 mm. The shape and size of the second openings 8a, 8b can also be designed arbitrarily, for example, they are rectangular, and the length of one side is about 6mm.

The relationship between the areas of the openings is that the area of one second opening 8a (or the second opening 8b) related to the protection element is smaller than the area of one first opening 7 related to the power generating element. Be big. Here, when the area changes with the position of the opening (for example, the depth position), the measurement position of the area can be defined arbitrarily. For example, the area may be measured at the lower end of each opening, or the area may be measured at the upper end of each opening. In the present embodiment, the area of the second opening 8 a (or the second opening 8 b ) is larger than the area of the first opening 7 using any of these measuring methods.

As shown in FIG. 2 , the semiconductor substrate 2 has a plurality of first openings 7 , one second opening 8 a , and one second opening 8 b with their insides removed. Among both surfaces of the semiconductor substrate 2 , the first insulating film 3 is formed on portions other than the openings. On the first insulating film 3, the first opening 7 is formed, and the first electrodes 4a, 4b, 4c are formed so as to cover the second openings 8a, 8b, and the electrolyte membranes 5a, 5b, 5c are formed thereon. , on which the second electrodes 6a, 6b, 6c are formed.

That is, the first opening 7, the second opening 8a, and the second opening 8b are all formed with a thin-film structure based on the same film configuration. That is, the power generating element portion and the protection element portion have the same film configuration. According to such a structure, the calculation process at the time of designing the withstand voltage strength of a power generation element part and a protection element part is simplified. In addition, the "film structure" here means, for example, the composition, thickness, and lamination order of each layer, and does not necessarily include the area of the film.

3A to 3D are diagrams showing the manufacturing steps of the fuel cell 1 . These figures correspond to the partial sectional view of FIG. 2 . First, as shown in FIG. 3A , prepare a semiconductor substrate 2 composed of single crystal silicon with a crystal orientation of silicon <100>. The semiconductor substrate 2 has a thickness of, for example, 400 μm or more.

The first insulating film 3 is formed on the surface of the semiconductor substrate 2 . As the first insulating film 3, for example, a silicon nitride film having a tensile stress of about 200 nm is formed by CVD. In the case of the CVD method, silicon nitride films having the same film thickness are formed on the upper side and the lower side of the semiconductor substrate 2 .

Next, a metal film (for example, a platinum (Pt) film) is formed to a thickness of about 100 nm by a sputtering method. Next, as shown in FIG. 3A , first electrodes 4 a , 4 b , and 4 c are formed. This is performed by patterning using a lithography method, a dry etching method using argon (Ar) gas, or the like.

At this time, in order to increase the adhesive force between the platinum film and the first insulating film 3, it is preferable to modify the surface of the first insulating film 3 first. The modification is carried out, for example, by etching the surface of the first insulating film 3 (for example, by only about 10 to 15 nm) by sputter etching with argon gas before forming the platinum film.

Alternatively, in order to improve the adhesion between the platinum film and the first insulating film 3 , a titanium (Ti) film or an aluminum (Al) film may be formed with a thickness of about 2 nm as a barrier metal film that facilitates adhesion.

Next, a negative photoresist pattern is formed by photolithography. Next, a YSZ film (yttrium-containing zirconia film) of, for example, about 500 nm is formed as an electrolyte film by sputtering. Thereafter, the negative photoresist is removed. Thereby, as shown in FIG. 3B, electrolyte membranes 5a, 5b, 5c are formed.

Next, a platinum film of about 100 nm was formed by a sputtering method. Next, patterning is performed by a photolithography method, and by dry etching using argon gas, as shown in FIG. 3C , the second electrodes 6a, 6b, and 6c are formed.

Next, as shown in FIG. 3D , a part of the first insulating film 3 on the lower side of the semiconductor substrate 2 is removed using photolithography and insulating film etching technology, so that the back surface of the semiconductor substrate 2 is exposed.

Next, using the patterned first insulating film 3 on the lower surface of the semiconductor substrate 2 as a mask, a plurality of first openings 7 and second openings 8a, 8b are formed. This is performed by, for example, removing the silicon film of the semiconductor substrate 2 by wet etching with a potassium hydroxide (KOH) solution or a tetramethylamide (TMAH) solution. In addition, the silicon film of the semiconductor substrate 2 is removed by dry etching using a fluorine-based gas as a main component. In this way, the fuel cell 1 shown in FIGS. 1 and 2 is formed.

In addition, as suitable materials for the first electrodes 4a, 4b, 4c and the second electrodes 6a, 6b, 6c, excellent resistance to fluorine-based chemicals, low resistivity, and higher melting point than the use temperature (such as above 600°C). For example, a platinum film, silver (Ag) film, nickel (Ni) film, chromium (Cr) film, palladium (Pd) film, ruthenium (Ru) film, rhodium (Rh) film, etc. can be used besides the platinum film.

In addition, the first insulating film 3 is not limited to a silicon nitride film, and an insulating film (such as an aluminum nitride film) having tensile stress on a silicon substrate is suitable. In addition, the first insulating film 3 may be a silicon nitride film, a silicon oxide film containing boron or phosphorus, or a laminated film including a P-TEOS film containing an organic component at low temperature.

FIG. 4 is a graph showing the relationship between the area of the opening and the pressure resistance of the thin film for the fuel cell 1 in FIG. 1 . Four rectangular openings were formed with side lengths of 3 mm (opening area 9 mm ² ), 4 mm (opening area 16 mm ² ), 5 mm (opening area 25 mm ² ), and 6 mm (opening area 36 mm ² ). After forming a thin film of the membrane configuration of FIG. 2 on each opening, air was blown out, and the pressure at which the thin film was broken (membrane withstand pressure) was measured.

From the results in FIG. 4 , it can be seen that the withstand voltage of the thin film decreases as the area of the opening increases. In Embodiment 1, the length of one side of the second openings 8a and 8b is 6mm, so the withstand pressure of the protection element is about 25KPa. On the other hand, the length of one side of the first opening 7 is 5 mm, and the withstand pressure of the power generating element part is about 32 KPa.

In this way, the withstand voltage of the membrane is different, and the withstand voltage strength of the protective element portion is lower than that of the power generating element portion. That is, the strength of the film or laminate constituting the protective element portion is relatively lower than the strength of the film or laminate constituting the power generating element portion. That is, when a sudden pressure fluctuation occurs, the protection element portion is damaged before the power generation element portion. Also, in Embodiment 1, the ratio of the compressive strength is about 1.3.

Fig. 5 is a plan view of the partition plate 9 according to Embodiment 1 of the present invention. Fig. 6 is a sectional view along line B-B of Fig. 5 . The separator 9 is arranged in contact with the fuel cell 1 .

The upper side groove 11 and the lower side groove 13 are formed in the separator 9 . The upper groove 11 is formed on the upper surface of the ceramic substrate 10 . The upper groove 11 includes a gas inlet 11 a, a gas outlet 11 b, and a through hole 12 . The through hole 12 penetrates the ceramic substrate 10 up and down.

The lower groove 13 is formed on the lower surface of the ceramic substrate 10 . The lower groove 13 includes an air inlet 13 a, an air outlet 13 b, and a through hole 14 . The through hole 14 penetrates the ceramic substrate 10 up and down.

The external dimensions of the separator 9 are almost the same as those of the fuel cell 1 . In this embodiment, the upper side groove 11 of the separator 9 extends over the range including the entire first opening 7 of the fuel cell 1 and the entire second opening 8a when viewed from above. Therefore, when the fuel cells 1 are respectively arranged on the upper and lower sides of the separator 9 (for example, as described later in relation to FIG. 7 ), the gas permeates through the upper side groove 11 and diffuses to the first electrode 4a of the upper fuel cell 1, and the upper side The first electrode 4b of the fuel cell 1 on the lower side and the second electrode 6b of the fuel cell 1 on the lower side.

Similarly, in this embodiment, the lower groove 13 of the separator 9 extends over the entire first opening 7 of the fuel cell 1 and the entire second opening 8b when viewed from above. Therefore, when the fuel cells 1 are arranged above and below the separator 9, the gas passes through the lower groove 13 and diffuses to the second electrode 6a of the fuel cell 1 on the lower side, and the second electrode 6c of the fuel cell 1 on the lower side. , the first electrode 4c of the fuel cell 1 on the upper side.

As shown in FIG. 6 , the upper groove 11 includes through-holes 12 and serves as a flow channel for a certain gas, and the lower groove 13 includes through-holes 14 and serves as a flow channel for another gas. However, since the upper groove 11 and the lower groove 13 are shielded by the substrate of the spacer 9, these two kinds of gases do not mix. In particular, the through hole 12 does not communicate with the lower groove 13, and the through hole 14 does not communicate with the upper groove 11, so the fuel gas is separated from the air and sent to the fuel cell.

In this way, the separator 9 is disposed on the fuel cell 1 to separate fuel gas and air. According to such a configuration, mixing of fuel gas and air can be prevented.

FIG. 7 is a cross-sectional view of the fuel cell module 15 related to the first embodiment. The fuel cell module 15 has two fuel cell cells 1 and one separator 9 . Above and below the separator 9, each fuel cell 1 is arranged.

As shown in FIG. 7 , in the fuel cell module 15 , two fuel cell cells 1 are stacked. A separator 9 is laminated between two fuel cell cells 1 . On the upper end and the lower end of the fuel cell module 15, an upper substrate 17 and a lower substrate 16 respectively having gas flow channels are provided.

Furthermore, the flow path of the lower substrate 16 is a groove having the same shape as the upper groove 11 of the separator 9 except for the portion of the through hole 12 . The flow path of the lower substrate 16 is provided with at least two openings on the side surface so that gas can flow in and out. Similarly, the flow path of the upper substrate 17 is a groove having the same shape as the lower groove 13 of the separator 9 except for the portion of the through hole 14 . The flow path of the upper substrate 17 is also provided with at least two openings on the side surface so that the gas can flow in and out.

The fuel cell module 15 has a mechanism (not shown) that applies pressure to the lower substrate 16 and the upper substrate 17 . Thereby, the airtightness of the area where the fuel gas and air circulate is maintained, and the mixing of gases is prevented.

In this configuration, the fuel gas 18 is supplied from the right side of the paper in FIG. 7 . The fuel gas 18 reaches the following electrodes. - The first electrode 4b and the second electrode 6b of the protective element portion of the upper fuel cell 1 - The first electrode 4a of the power generation element part of the fuel cell 1 on the upper side - The first electrode 4b and the second electrode 6b of the protection element part of the fuel cell 1 on the lower side - The first electrode 4a of the power generating element part of the fuel cell 1 on the lower side In addition, fuel gas 18 consumed in power generation is discharged from a gas discharge port not shown.

Similarly, the air 19 is supplied from the left side of the paper in FIG. 7 . Air 19, reaches the following electrodes. - The first electrode 4c and the second electrode 6c of the protective element portion of the upper fuel cell 1 - The second electrode 6a of the power generating element part of the fuel cell 1 on the upper side - The first electrode 4c and the second electrode 6c of the protective element portion of the fuel cell 1 on the lower side - The second electrode 6a of the power generating element part of the fuel cell 1 on the lower side In addition, the air 19 consumed in power generation is discharged from a gas discharge port not shown.

That is, the fuel gas 18 and the air 19 are supplied, consumed, and discharged in a separated state by the separator 9 , the lower substrate 16 , and the upper substrate 17 . Also, although not shown, in the fuel cell module 15, pressure is applied between the upper substrate 17 and the lower substrate 16 so that the fuel gas 18 and the air 19 do not leak.

In FIG. 7 , the fuel gas 18 is supplied from three positions of upper/middle/lower on the right side of the paper, but it is assumed, for example, that the pressure rises sharply only in the middle of these. In the upper fuel cell 1 , the power generating element portion and the right protection element portion receive a pressure difference, and in the lower fuel cell 1 , the right protection element portion receives a pressure difference. However, either one (or both) of the two protection element parts is damaged earlier than the power generation element part, so the pressure difference between the stages is reduced, so the damage of the power generation element part is avoided.

In addition, it can be seen from the foregoing that both the fuel gas 18 and the air 19 are supplied to the power generating element portion, and only one of the fuel gas 18 or the air 19 is supplied to the protective element portion. Therefore, the protection element part has a structure capable of generating electricity in this embodiment, but does not actually generate electricity as shown in FIG. 7 . Thus, by adopting a configuration in which the operation of the protective element unit does not affect the power generation, even if the protective element unit is damaged, the influence on the power generation operation of the fuel cell 1 can be avoided. In addition, in Embodiment 1, such a structure is realized by the spacer 9 having the through-holes 12 and 14 at the positions corresponding to the protective element parts.

Between the fuel cell 1 and the separator 9 , between the fuel cell 1 and the upper substrate 17 , and/or between the fuel cell 1 and the lower substrate 16 , a sealing material having good heat resistance may be used. As the sealing material, a material that deforms when pressure is applied can reduce damage to the fuel cell 1 when pressure is applied.

In addition, the fuel cell module 15 of Embodiment 1 has a structure in which two fuel cell cells 1 are laminated, and may be formed by stacking more stages by overlapping the fuel cell cells 1 and separators 9 alternately. With such a configuration, the desired output can be obtained.

FIG. 8 shows a schematic diagram of a fuel cell system related to Embodiment 1. As shown in FIG. The main components of the fuel cell system include a blower 21 for sending out fuel gas 18 and air 19, a reformer 22 with a fuel gas flow adjustment mechanism, a pressure regulator 23 for adjusting the pressure of air, a fuel cell module 15, and a fuel cell module 15. The battery module 15 is provided with a case 24 for keeping the battery module 15 at a constant temperature (300° C. to 600° C.), and a burner 25 for burning the discharged fuel gas.

For example, methane can be used as fuel gas 18 . The methane is blown by the blower 21, and the flow rate and pressure are adjusted in the reformer 22. Thereby, hydrogen-containing fuel gas of about 600° C. is generated. The fuel gas is sent to the fuel cell module 15 .

In addition, the air 19 is also blown by the blower 21 , the pressure and flow are adjusted by the pressure regulator 23 , and sent to the fuel cell module 15 . Furthermore, the temperature of the air is also about 600° C. by the heat of the reformer 22 .

The flow rates of fuel gas and air need to be increased to, for example, several liters/minute at the time of maximum output.

Thereafter, the reformed fuel gas 18 and the heated air 19 are piped through the housing 24 kept at about 500° C. and sent to the fuel cell module 15 to be consumed for power generation. Thereafter, the consumed gases are combined in the burner 25 through the pipes, combusted at high temperature, and discharged.

Also, although not shown, pressure gauges and flowmeters are provided in piping for fuel gas and air discharged from the fuel cell module 15 . Thereby, feedback control is performed on the reformer 22 and the pressure regulator 23, and the average pressure and flow rate in the piping are adjusted.

Since it is difficult to maintain the temperature of the piping before the casing 24 , heat may be generated to expand or contract the gas until it reaches the fuel cell module 15 . In addition, since the diameter of the piping is reduced at the portion entering the fuel cell 1 , a sudden and instantaneous pressure fluctuation may occur. This tendency occurs more easily when the power generation of the fuel cell 1 is performed with high efficiency, and the pressure fluctuation due to the temperature change becomes larger.

Pressure fluctuations of fuel gas 18 and air 19 are generated across the thin films (first electrodes 4a, 4b, 4c, electrolyte membranes 5a, 5b, 5c, second electrodes 6a, 6b, 6c) of the power generating element and protective element . Moreover, this pressure fluctuation often occurs suddenly, and it is often difficult to cope with it even if feedback control is applied to the reformer 22 and the pressure regulator 23 .

In the fuel cell 1 of Embodiment 1, a protective element portion having a large area is provided near the gas inlet. In addition, the withstand voltage strength of the protection element part is set to be lower than the withstand voltage strength of the power generation element part. Therefore, when a sudden pressure fluctuation occurs, the protective element portion is damaged before the power generation element portion is damaged.

When the protective element part is damaged, a gas channel passing through the damaged protective element part is formed, so that the gas flow can be diverged, the pressure difference can be reduced, and the pressure fluctuation can be eased. That is, it is possible to reduce the influence on the power generating element portion and prevent damage to the power generating element portion.

In addition, due to the structure of the separator 9, even if the protective element part is damaged, the fuel gas 18 and the air 19 are not mixed, so adverse effects due to gas mixing can be prevented.

Thus, according to Embodiment 1, by providing the protection element portion, even when the pressure difference between the fuel gas and the oxidant gas fluctuates rapidly or increases excessively, damage to the power generation element portion can be prevented. Thereby, a highly reliable and highly efficient fuel cell system can be provided.

In addition, according to the relationship between the opening area and the pressure resistance of the thin film shown in Fig. 4, by designing the opening area of the protection element, the limit value of pressure fluctuation can be controlled. When the opening area of the power generating element portion is changed, the opening area of the protection element portion can be changed accordingly.

In addition, damage to the protective element can be detected by monitoring the capacitance value between the first electrode and the second electrode of the protective element, or by monitoring the resistance value of the first electrode or the second electrode. When damage to the protective element portion is detected, the fuel cell module can be stopped safely. After stopping, only the damaged fuel cells can be replaced to generate electricity again. In this way, maintenance can be easily performed.

When a plurality of fuel cell cells 1 are stacked, even if one of the protective element parts is damaged, the structure of the power generating element part will not be affected. In addition, in Embodiment 1, the fuel gas and the air are separated and flowed, so the power generation operation can be continued.

In Embodiment 1, methane is used as the fuel gas, but it is not particularly limited as long as it is a gas that can be reformed. For example, natural gas, LP gas (liquefied petroleum gas), coal reformed gas, lower hydrocarbon gas (ethane, ethylene, propane, butane), bioethanol, etc. can be used as hydrocarbon fuel. In addition, a vaporizer may be provided in the preceding stage of the reformer 22, and moisture may be vaporized from the raw material gas (or liquid) of hydrocarbon fuel by the vaporizer.

For the fuel cell module, an example is given in which the fuel cell cells 1 are stacked up and down, but they may also be arranged in the horizontal direction. In this case, the gas may flow from bottom to top.

＜Implementation Type 2＞ FIG. 9 is a plan view of a fuel cell 26 according to Embodiment 2 of the present invention. Fig. 10 is a sectional view along line C-C of Fig. 9 . The second electrode of the protection element unit is configured as a temperature sensor 27 . The temperature sensor 27 may be a wiring arranged on the second openings 8a, 8b. Unlike Embodiment 1, the wiring of the temperature sensor 27 is formed only in a part of the second openings 8a and 8b.

In addition, both ends of the wiring of the temperature sensor 27 can be arranged so as to be connectable to the outside. In the fuel cell 26, the configuration other than the protection element portion (including the configuration of the power generation element portion) can be the same as that of the first embodiment.

In the fuel cell 26 according to the second embodiment, the temperature of the protective element can be measured by the temperature sensor 27 formed in the protective element. The temperature can be measured by, for example, detecting the resistance value of the wiring of the temperature sensor 27 and converting the resistance value into the temperature of the gas. Abnormalities can be detected by monitoring the temperature of the gas. Additionally, by monitoring the temperature of the gas, feedback can be provided to the adjustment of the pressure, flow, and/or temperature of the gas. Thereby, stable power generation can be performed.

Moreover, the material of the membrane of the protective element portion is the same as that of Embodiment 1, and the membrane structure is also almost the same, so similar to Embodiment 1, the effect as a safety valve against sudden pressure fluctuations of fuel gas and the like is exhibited.

A flow rate adjustment valve may be provided at the gas inflow port into each fuel cell 26 to control the value of the temperature measured by the temperature sensor 27 within a certain range. For example, the gas temperature can be measured in a steady state, and when the protective element part is damaged due to a sudden pressure change, the wiring of the temperature sensor 27 is disconnected, so the damage can be detected. That is, the temperature sensor 27 functions as a detection unit that detects breakage of the protection element unit. This provides a fuel cell system capable of detecting breakage of the protective element and performing stable power generation output.

Also, in Embodiment 2, a temperature sensor 27 is provided on the protection element part, but other sensors (such as pressure sensors using piezoelectric elements, vibration sensors, etc.) can also be provided, and multiple sensors can also be provided. sensor. In addition, in Embodiment 2, the wiring to be a temperature sensor is formed as the second electrode on the upper side of the electrolyte membrane 5b, 5c, but as a modified example, it may be formed as the first electrode on the lower side of the electrolyte membrane 5b, 5c. 4b, 4c.

＜Implementation Type 3＞ FIG. 11 is a plan view of a fuel cell 28 according to Embodiment 3 of the present invention. Fig. 12 is a sectional view taken along line D-D of Fig. 11 . In the fuel cell 28 related to Embodiment 3, the single area of the second openings 8a, 8b related to the protection element is formed so that the area of the single first opening 7 related to the power generating element is approximately the same. equal. Thereby, the area occupied by the protection element portion becomes smaller than that of Embodiment 1, and more power generation element portions can be arranged.

In Embodiment 3, the film structure of the protective element part is different from the film structure of the power generating element part. In the protective element portion, the first electrode and the electrolyte membrane are not formed. In addition, a second insulating film 29 is formed instead of the second electrode, and the same temperature sensor 27 as in Embodiment 2 is disposed thereon.

The structure of the second insulating film 29 can be appropriately designed in accordance with the relationship between the area of the opening with respect to the protective element portion and the withstand voltage of the film. For example, for the second insulating film 29 of various structures, the area of the opening can be changed in various ways to measure the film withstand voltage, so that the withstand voltage strength of the protection element part is lower than that of the power generation element part. The structure of the second insulating film 29 and the area of the opening.

The second insulating film 29 is preferably an insulating film having tensile stress on the silicon substrate, and for example, a silicon nitride film, an aluminum nitride film, or the like can be used. In addition, the second insulating film 29 may also be a laminated film of a film having tensile stress on the silicon substrate and a film having compressive stress on the silicon substrate, for example, a silicon nitride film, and a film containing boron or phosphorus. The laminated film of the silicon oxide film may also be a laminated film of a silicon nitride film and a P-TEOS film containing an organic component at a low temperature.

The film withstand voltage of the second insulating film 29 can be controlled by changing the film thickness, so that the film withstand voltage is preferably lower than that of the power generating element portion. That is, if the membrane withstand voltage is lower than that of the power generating element part, the area of the second openings 8a, 8b may be smaller than the area of the first opening 7 related to the power generating element part.

As a modified example of Embodiment 3, the second insulating film may be formed by a thinned electrolyte film, or may be formed by leaving the first insulating film 3 .

In Embodiment 3, by making the area of the opening related to the protection element part smaller than in Embodiment 1, more power generating element parts in the fuel cell cells 28 can be arranged, and the area of the power generating region can be further expanded. . Thereby, power generation output becomes higher.

＜Implementation Type 4＞ Fig. 13 is a plan view of a separator 30 according to Embodiment 4 of the present invention. Fig. 14 is a cross-sectional view along line E-E of Fig. 13 . The separator 30 of Embodiment 4 is constituted by, for example, a ceramic substrate 31 . On the upper surface side of the ceramic substrate 31, an upper side groove 32 for a fuel gas inlet 32a and a gas outlet 32b, and an upper side groove 33 for air gas are formed. On the lower surface side of the ceramic substrate 31, a lower groove 34 having an air inlet 34a and an air outlet 34b, and a lower groove 35 for fuel gas are formed.

Like the separator 9 of Embodiment 1, the external dimensions of the separator 30 are almost the same as those of the fuel cell 1 . In this embodiment, the upper groove 32 of the separator 30 extends over the entire first opening 7 of the fuel cell 1 and the entire second opening 8a when viewed from above. Therefore, when the fuel cells 1 are arranged on the upper and lower sides of the separator 30 (for example, as described later in relation to FIG. The first electrode 4b of the fuel cell 1.

Similarly, in this embodiment, the lower groove 34 of the separator 30 extends over the entire first opening 7 and the entire second opening 8b of the fuel cell 1 when viewed from above. Therefore, when the fuel cell 1 is arranged on the upper and lower sides of the separator 30, the gas permeates through the lower groove 34 and diffuses to the second electrode 6a of the lower fuel cell 1 and the second electrode 6c of the lower fuel cell 1. .

As shown in FIG. 14 , as a difference from the spacer 9 related to Embodiment 1, the spacer 30 does not have a through hole penetrating the ceramic substrate 31 up and down. On the top side and the bottom side of the ceramic substrate 31 , grooves for supplying fuel gas and air are respectively formed. Therefore, each gas is separated and sent to the fuel cell 1 .

FIG. 15 is a sectional view of the fuel cell module 40 related to the fourth embodiment. In the fuel cell module 40, two fuel cell cells 1 are stacked. A separator 30 is laminated between two fuel cell cells 1 . On the upper end and the lower end of the fuel cell module 40, an upper substrate 17 and a lower substrate 16 respectively having gas flow channels are provided. In addition, the lower substrate 16 and the upper substrate 17 have the same configuration as that of the first embodiment.

In this configuration, the fuel gas is divided into fuel gas 36 and fuel gas 37 . The fuel gas 36 passes through the plurality of first openings 7 and second openings 8a, and is sent to the first electrodes 4a, 4b. The fuel gas 37 is sent to the second electrode 6b of the protective element portion.

Air is divided into air 38 and air 39 . The air 38 is sent to the second electrode 6a of the power generating element part and the second electrode 6c of the protective element part. The air 39 is sent to the first electrode 4c of the protective element portion through the second opening 8b.

That is, the fuel gas 36 and the air 38 are fed to the power generating element portion to generate power. On the other hand, the fuel gas 36 and the fuel gas 37 are supplied to the protective element portion, or the air 38 and the air 39 are supplied.

In Embodiment 4, the separator 30 does not have a through hole, so even if the protective element part is damaged due to a sudden pressure change of fuel gas or air, the fragments of the damaged protective element part will not be scattered up and down or fly off. other protective components. Therefore, damage to one fuel cell does not affect other fuel cells. That is, a highly reliable fuel cell system can be provided.

Also, when the protective element part is damaged, it is appropriate to control the pressure of the fuel gas 37 to be slightly lower than the pressure of the fuel gas 36 so that the fragments do not scatter to the power generating element part. The same is true for air, and it is appropriate to control the pressure of the air 39 to be slightly lower than the pressure of the air 38 .

＜Other modifications＞ The present invention is not limited to the aforementioned embodiments and modifications thereof, but also includes other various modifications. For example, the foregoing embodiments have been described in detail to facilitate understanding of the present invention, but the present invention is not limited to having all the configurations described above. In addition, it is also possible to replace a part of the configuration of a certain embodiment type with the configuration of another embodiment type, and it is also possible to add the configuration of another embodiment type to the configuration of a certain embodiment type. In addition, it is possible to add, delete, or substitute other configurations for a part of the configurations of each embodiment.

1,26,28: fuel cell 2: Semiconductor substrate 3: The first insulating film 4a, 4b, 4c: 1st electrode (conductive film) 5a, 5b, 5c: electrolyte membrane 6a, 6b, 6c: 2nd electrode (conductive film) 7: The first opening 8a, 8b: the second opening 9,30: Partition 10,31: ceramic substrate 11,32,33: upper side groove 11a, 32a: gas inlet 11b, 32b: Gas outlet 12,14: Through hole 13a, 34a: Air inlet 13b, 34b: Air outlet 13,34,35: lower lateral groove 15,40: Fuel Cell Module 16: Lower side substrate 17: Upper substrate 18,36,37: fuel gas 19,38,39: Air (oxidant gas) 21: blower 22: Reformer 23: Pressure regulator 24: Housing 25: Burner 27: Temperature sensor (detection part) 29: Second insulating film

[FIG. 1] A plan view of a fuel cell related to Embodiment 1. [FIG. [ Fig. 2 ] is a sectional view taken along line A-A of Fig. 1 . [FIG. 3A] is a sectional view showing the manufacturing steps of the fuel cell shown in FIG. 1. [FIG. [ Fig. 3B ] is a cross-sectional view showing the manufacturing steps of the fuel cell shown in Fig. 1 . [FIG. 3C] is a sectional view showing the manufacturing steps of the fuel cell shown in FIG. 1. [FIG. [ Fig. 3D ] is a cross-sectional view showing the manufacturing steps of the fuel cell shown in Fig. 1 . [Fig. 4] is a graph showing the relationship between the area of the opening and the withstand voltage of the thin film. [FIG. 5] It is a plan view of the fuel cell separator related to Embodiment 1. [FIG. [ Fig. 6 ] is a cross-sectional view taken along line B-B in Fig. 5 . [ Fig. 7 ] is a cross-sectional view of the fuel cell module related to Embodiment 1. [ Fig. 8 ] A schematic diagram of a fuel cell system related to Embodiment 1. [ Fig. 8 ]. [FIG. 9] A plan view of a fuel cell related to Embodiment 2. [FIG. [ Fig. 10 ] is a sectional view along line C-C of Fig. 9 . [FIG. 11] A plan view of a fuel cell related to Embodiment 3. [FIG. [ Fig. 12 ] is a sectional view taken along line D-D in Fig. 11 . [ Fig. 13 ] is a plan view of a fuel cell separator related to Embodiment 4. [ Fig. 13 ]. [ Fig. 14 ] is a sectional view taken along line E-E of Fig. 13 . [ Fig. 15 ] is a sectional view of the fuel cell module related to the fourth embodiment.

1: Fuel cell

2: Semiconductor substrate

3: The first insulating film

4a, 4b, 4c: 1st electrode (conductive film)

5a, 5b, 5c: electrolyte membrane

6a, 6b, 6c: 2nd electrode (conductive film)

7: The first opening

8a, 8b: the second opening

Claims (10)

A fuel cell comprising: a power generating element portion formed by laminating an electrolyte film and one or more conductive films, which is supplied with a fuel gas and an oxidant gas to generate power; The protective element part of one side of the oxidant gas; the compressive strength of the protective element part is lower than that of the power generating element part, and the damage of the protective element part is ensured before the damage of the power generating element part occurs. The fuel cell according to claim 1, wherein the protective element part further includes a detection part for detecting damage to the protective element part. The fuel cell according to claim 1, wherein the power generation element portion and the protection element portion are formed on the same substrate. The fuel cell cell according to claim 1, wherein the power generating element portion and the protective element portion are formed in a plurality of openings of the substrate, and the area of one opening relative to the protective element portion is larger than that of the power generating element portion The area of one of the openings is even larger. The fuel cell according to claim 1, wherein the power generating element part is formed in a plurality of openings of the substrate, the power generating element part is provided with a plurality of the conductive films, and at least one of the conductive films is continuous across the plurality of openings . The fuel cell according to claim 1, wherein the protective element portion is provided with a conductive film, and one of the conductive films of the power generating element portion is continuous with the conductive film of the protective element portion. The fuel cell according to claim 1, wherein the power generating element part and the protective element part have the same membrane structure. The fuel cell according to claim 1, wherein the protection element part does not generate electricity. A fuel cell module comprising the aforementioned fuel cell cell according to claim 1, and a separator arranged in the aforementioned fuel cell cell to separate the aforementioned fuel gas and the aforementioned oxidant gas. The fuel cell module according to claim 9, wherein the separator has a through hole at a position corresponding to the protective element.

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