JP4654079B2 - Solid oxide fuel cell - Google Patents

Description

The present invention relates to an arrangement of electrochemical cells for generating unit electromotive force in a solid oxide fuel cell.

A solid oxide fuel cell (SOFC) is characterized in that the constituent material is solid and the operating environment is high temperature. In the old days, it was put to practical use with flat and cylindrical solid oxide fuel cells. However, the cylindrical SOFC has a drawback that the output density per unit volume is low, and the flat plate SOFC has a difficult problem in the sealing method and the like.

Therefore, in recent years, a plurality of inventions have been made for honeycomb-shaped SOFCs. Japanese Patent Application Laid-Open No. 10-40934 is exemplified as Patent Document 1, and the claims, paragraphs 0006 to 0012 and drawings of the detailed description of the invention are shown. Japanese Patent Application Laid-Open No. 2003-51319 is exemplified as Patent Document 2, and the claims, paragraphs 0007 to 0015 of the detailed description of the invention, and FIGS. The search range of the background art patent of this application was F-term 5H026, AA06, CV04 or CV06, and extracted from these.

Japanese Patent Laid-Open No. 10-40934 JP 2003-51319 A

Patent Document 1 describes a basic arrangement structure of an electrochemical cell having a honeycomb structure. It is described that SOFC having a honeycomb structure has a large electrode area per unit volume and high efficiency.
Claim 2 of Patent Document 2 includes a fuel cell that uses a mixed gas and has a large power generation output in order to increase power generation efficiency, and a battery element in which a solid electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer. There has been disclosed an invention in which two or more parts are provided and a plurality of battery element parts are arranged in series on one cell plate.

It is an object of the present invention to provide a fuel cell that uses both fuel gas and air gas and can obtain a large output voltage and output current per unit cell element.

In the fuel cell according to the first aspect of the present invention, the airtight solid electrolyte material having a honeycomb structure is used as the partition, and the plurality of first gas passages, the plurality of second gas passages, and the first gas are provided. A first electrode facing the flow path (hereinafter also referred to as a first electrode), and a second electrode facing the second gas flow path (hereinafter also referred to as a second electrode). In a solid oxide fuel cell comprising: a single or a plurality of first gas flow paths, a single or a plurality of second gas flow paths, a first electrode, a second electrode, a gas of the first electrode Of the part of the solid oxide fuel cell comprising the first electrode terminal provided at the end of the flow path and the second electrode terminal provided on the opposite side of the first electrode terminal , one electrically All connected first electrodes, all electrically connected second electrodes, a first gas facing the first electrode A second gas flow path facing the second electrode, a first electrode terminal that electrically connects the first electrodes together, and a second that electrically connects the second electrodes together. The electrode terminals of the plurality of electrochemical cells are arranged as a unit, and a plurality of the electrochemical cells are juxtaposed on the same plane, and the solid electrolyte materials of the plurality of electrochemical cells have an integrated structure without being separated from each other. None, two adjacent electrochemical cells in juxtaposition are either the first electrode terminal or the second electrode terminal, either of which is electrically connected, and a plurality of electrochemical cells are connected in series It is a summary.

In the fuel cell according to claim 2 of the present invention, in addition to the invention of claim 1, one unit of electrochemical cell according to claim 1 includes a plurality of first gas flow paths and a plurality of second gas flow paths. The gist is to have.

According to the invention of claim 1 of this application, a fuel cell having a large output voltage can be obtained with a simple structure without stacking unit cells. In the fuel cell of the present invention, an interconnector required for a flat plate fuel cell or a cylindrical fuel cell is not required.

In the invention of claim 2, one unit of electrochemical cell is a collection of a plurality of unit electromotive forces, and the output current per unit volume can be increased.

The components of the present invention will be described below in order.
The fuel cell according to the present invention is a honeycomb fuel cell having an airtight solid electrolyte material as partition walls, and is characterized by its electrode arrangement.

In the honeycomb fuel cell, portions corresponding to the holes of the honeycomb are used as the fuel gas flow path and the air gas flow path. In the present invention, the fuel gas passage and the air gas passage are named as the first gas passage and the second gas passage in any order. In addition, an airtight solid electrolyte material is used as a partition wall at a portion corresponding to the honeycomb wall, and a cathode or an anode is formed at a portion facing the fuel gas channel or the air gas channel. In the present invention, the plurality of cathodes or anodes are named as the first electrode or the second electrode.

The shape of the honeycomb is not particularly limited, but from the viewpoint of space utilization efficiency, it is preferable that the cross-sectional shape of each opening is an isosceles triangle, regular triangle, rectangle, square, regular hexagon, or the like that can fill a flat surface without a gap. In addition, a design in which openings having different shapes such as a regular triangle and a regular hexagon are adjacent to each other is possible.

The solid electrolyte material is preferably yttria stabilized zirconia or yttria partially stabilized zirconia, but other materials can also be used. In the case of a NOx decomposition cell, cerium oxide is also preferable.

In the present invention, the fuel gas flow path and the air gas flow path are used as the first gas flow path and the second gas flow path in any order, but this is the fuel gas flow path or the air gas flow path. If the fuel gas channel and the air gas channel are set on both sides of the partition wall of the solid electrolyte material, an electromotive force is generated.

The main raw material of the cathode that faces the fuel gas channel is preferably a perovskite type complex oxide containing lanthanum, more preferably lanthanum manganite or lanthanum cobaltite, and lanthanum manganite. Even more preferred. Lanthanum chromite and lanthanum manganite may be doped with strontium, calcium, chromium (in the case of lanthanum manganite), cobalt, iron, nickel, aluminum or the like. Also, palladium, platinum, ruthenium, platinum-zirconia mixed powder, palladium-zirconia mixed powder, ruthenium-zirconia mixed powder, platinum-cerium oxide mixed powder, palladium-cerium oxide mixed powder, ruthenium-cerium oxide mixed powder Good.

The main raw materials of the anode that will face the air gas flow path are nickel, palladium, platinum, nickel-zirconia mixed powder, platinum-zirconia mixed powder, palladium-zirconia mixed powder, nickel-cerium oxide mixed powder, platinum- Preferred are cerium oxide mixed powder, palladium-cerium oxide mixed powder, ruthenium, ruthenium-zirconia mixed powder and the like.

In this invention, the electrochemical cell uses a solid electrolyte material for generating unit electromotive force as a partition, and includes a first gas channel, a second gas channel, and a first gas channel facing the first gas channel. An electrode consists of a second electrode facing the second gas flow path. If there are cases where this electrochemical cell is constituted by a single first gas flow path and a single second gas flow path, it is constituted by a plurality of first gas flow paths and a plurality of second gas flow paths. Sometimes it is done. Further, the first or second electrode, the first or second gas flow path, and the partition wall around the electrode are collectively referred to as a fuel electrode cell in the case of a cathode and an air electrode cell in the case of an anode.

In the present invention, in order to take out electrons generated at the cathode or return electrons to the anode, an electrode terminal is provided at one end with respect to the gas flow path direction. The electrode terminals are provided so that the anode and the cathode are in opposite positions. In the claims, the expression gas channel end is used, but it may be the gas channel inlet. In addition, as shown in the longitudinal sectional view, the electrode is not formed on the entire surface of the gas flow path but on the side where the electrode terminal is not provided, so that no current flows directly between the electrodes, Do not form. The predetermined distance is determined in an optimum dimension in consideration of the solid electrolyte material, the electric conductivity of fuel, and air. The adopted distance is approximately 0.5 to 5.0 mm. Thus, electrode terminals are formed at the respective ends of the first electrode (for example, the cathode) and the second electrode (for example, the anode). When a plurality of fuel electrode cells or air electrode cells are formed, electromotive forces are collected at the electrode terminals.

In the present invention, a plurality of electrochemical cells are arranged on the same plane , and solid electrolyte materials of the plurality of electrochemical cells are not separated from each other to form an integral structure . At this time, two adjacent electrochemical cells are electrically connected to either the first electrode terminal or the second electrode terminal, and a plurality of electrochemical cells are connected in series.

The fuel cell of the present invention can be formed from any of the partition walls made of a honeycomb-shaped solid electrolyte, the first electrode, and the second electrode, but it is usually preferable to form the partition before the partition wall portion.

Hereinafter, an embodiment relating to an electrode arrangement of a fuel cell comprising a plurality of electrochemical cells embodying the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of the fuel cell of Example 1 when cut in a direction perpendicular to the gas flow path. The figure schematically shows the shape. In practice, the number of cells constituting the electrochemical cell, the number, size, or size ratio of the electrochemical cell can be adjusted and employed.

In the fuel cell of Example 1 shown in FIG. 1, three electrochemical cells 10 each having two first and second gas flow paths and two electrodes are arranged vertically and horizontally. One electrochemical cell as a unit is formed by arranging two first gas flow paths and two second gas flow paths having a square cross section at intersecting positions, and is divided by a honeycomb-shaped partition wall made of a solid electrolyte. It has been made. In the figure, a first electrode 2 is formed around the first gas flow path 1, and a second electrode 4 is formed around the second gas flow path 3. Yes. In the case of supplying air gas to the first gas flow path, the first electrode is an anode (also referred to as an air electrode), and fuel gas (for example, hydrogen gas is used) is used for the second gas flow path. The second electrode serves as a cathode (also referred to as a fuel electrode). Reference numeral 5 denotes a partition wall made of a solid electrolyte. In FIG. 1, the boundary between electrochemical cells that generate unit electromotive force is indicated by a broken line although it does not originally appear in the sectional view. In Example 1, two electrochemical cells each having two first electrodes and two second electrodes are used as one electrochemical cell, and the current is collected at the electrode terminals. It can be understood by combining the cross-sectional views.

Next, in FIG. 2, a plane viewed from one end of the gas flow path in order to explain the connection state of the electrode terminals denoted by reference numeral 6 formed in the electrochemical cell 10 in three vertical and horizontal directions shown in FIG. 1. FIG. When the second electrode 4 of the electrochemical cell located at the upper left of this plane is connected to the outside, the first electrode 2 is connected to the second electrode 4 of the second electrochemical cell on the opposite side of this plane. 2 is connected to the second electrode 4 of the electrochemical cell on the upper right side, and on the opposite side of this plane, the first electrode 2 on the upper right side is on the right on the middle stage. It is connected to the second electrode 4 of the electrochemical cell. Similarly, the middle stage electrochemical cells are connected in series from right to left, and the lower stage electrochemical cells are connected in series from left to right. Also in FIG. 2, the boundary between the partition walls is indicated by a solid line in order to clarify one unit of the electrochemical cell.

FIG. 3 shows a cross-sectional view of the honeycomb partition wall taken along the line AA in FIG. 2 when cut in a direction parallel to the gas flow path. When the gas flowing through the first gas flow path is an air gas, an anode is formed inside the first gas flow path, and when the gas flowing through the second gas flow path is a fuel gas, The cathode is formed inside the second gas flow path.

As FIG. 10, the model figure for showing the connection state of the electrochemical cell in this Example 1 is shown. FIG. 10 shows a model in which the first electrode is used as an anode and the second electrode is used as a cathode. In the figure, one electrochemical cell is shown as one battery. In Example 1, since three electrochemical cells are arranged in the vertical and horizontal directions, three rows of circuits indicating the connection state in one horizontal row are arranged. A resistor surrounded by a dotted line is added to consume power generated by the fuel cell. Since each electrochemical cell is relatively front and back, the side shown in the plan view of FIG. 2 is shown as the honeycomb surface for convenience, and the opposite side is the honeycomb back surface. As understood from this figure, either one of the electrochemical cell electrode terminals is connected to the electrode terminal of the adjacent electrochemical cell.

4 and 5 show a plan view in the second embodiment and a cross-sectional view taken along line BB in FIG. In the second embodiment, a part to be an electrode terminal in the first embodiment is partially changed. The difference between the electrode terminals in Example 1 and Example 2 is that, when compared in plan, Example 1 is provided with electrode terminals provided on two sides of the fuel electrode cell or the air electrode cell. In Example 2, the electrode terminals are provided on the four sides of the fuel electrode cell or the air electrode cell.

In Example 1 or Example 2, one electrochemical cell is exemplified by four honeycomb lattices. However, this number is six or nine, such as a larger number of electrochemical cells. It may be a chemical cell. In this case, the amount of current generated from one electrochemical cell can be made larger. In the figure, the first gas flow path and the second gas flow path are shown as having the same cross-sectional area. However, in order to increase the electromotive force or to control power generation, the cross-sectional area of each gas flow path is set. It is also possible to provide large and small.

6 to 9 show a third embodiment with reference to the drawings. Example 3 is a combination of four electrochemical cells, each having five gas flow paths . One electrochemical cell placed around the one first gas flow path are arranged a second gas flow path 4 on the four sides partition walls. In the other electrochemical cell, one second gas flow path is placed in the center, and four first gas flow paths are arranged on four sides of the partition wall. The channels other than the gas channel are cooling air channels through which a cooling air flow can flow. The fuel cell is electrically arranged such that its four electrochemical cells are in series. FIG. 6 shows a cross-sectional view when cut in a direction perpendicular to the gas flow path. In FIG. 6, the boundary between the electrochemical cells generating the unit electromotive force is indicated by a broken line although it does not originally appear in the sectional view. In FIG. 7, the top view seen from one inlet side of the gas flow path is shown. Also in FIG. 7, the boundary between the partition walls is shown by a solid line in order to clarify one unit of the electrochemical cell. 8 shows a cross-sectional view taken along line CC of FIG. 6, and FIG. 9 shows a cross-sectional view taken along line DD of FIG.

In FIG. 6 and subsequent figures, reference numerals 1 to 5 denote the same elements as those in the first or second embodiment. Reference numeral 7 denotes a cooling air flow path. When the second electrode located at the center of the upper left electrochemical cell shown in FIG. 7 is used as an extraction terminal to the outside by an electrode terminal, the electrode terminal of the first electrode on the opposite surface of FIG. It is connected to the electrode terminal of the second electrode in the chemical cell. The first electrode located at the center of the upper right electrochemical cell is connected to the second electrode at the center of the lower right electrochemical cell shown in the plan view. The first electrode of the lower right electrochemical cell is connected to the second electrode on the opposite surface of FIG.

In Example 3, one electrochemical cell is exemplified by one composed of nine honeycomb lattices. However, this electrochemical cell is composed of a larger number of electrochemical cells (for example, 5 rows × There are 25 honeycomb lattices with 5 columns or 49 honeycomb lattices with 7 rows × 7 columns. In this case, the amount of current generated from one electrochemical cell can be made larger. In the figure, the first gas flow path, the second gas flow path, or the cooling air flow path is shown as having substantially the same cross-sectional area. However, in order to increase the electromotive force or to control power generation, It is also possible to provide a large and small channel cross-sectional area.

The fuel cell of the present invention can be used by stacking a plurality of electrochemical cell assemblies shown in FIGS. 1 to 3 or FIGS. 6 to 9 in multiple stages. The number of layers is designed in consideration of the cell length of the electrochemical cell constituting one stage, the required output voltage, the material of the solid electrolyte to be selected, the size of the honeycomb cell, the overall heat balance, economy, etc. The

In the fuel cell of Example 1 of this invention, sectional drawing when cut | disconnected in the direction orthogonal to a gas flow path is shown. In the fuel cell of Example 1, the top view seen from one end of the gas flow path is shown. FIG. 3 shows a cross-sectional view of the honeycomb partition wall taken along the line AA in FIG. 2 when cut in a direction parallel to the gas flow path. In the fuel cell of Example 2 of this invention, the top view seen from one end of the gas flow path is shown. FIG. 5 shows a cross-sectional view of the honeycomb partition wall taken along the line BB in FIG. 4 when cut in a direction parallel to the gas flow path. In the fuel cell of Example 3 of this invention, sectional drawing when cut | disconnecting in the direction orthogonal to a gas flow path is shown. In the fuel cell of Example 3, the top view seen from one end of the gas flow path is shown. The CC sectional view taken on the line of FIG. 6 is shown. The DD sectional view taken on the line of FIG. 6 is shown. 2 is a model diagram for illustrating a connection state of an electrochemical cell in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st gas flow path 2 ... 1st electrode 3 ... 2nd gas flow path 4 ... 2nd electrode 5 ... Partition 6 ... Electrode terminal 7 ... Cooling air flow path 10 ... Electrochemical cell

Claims (2)

An airtight solid electrolyte material having a honeycomb-like structure is used as partition walls, a plurality of first gas passages, a plurality of second gas passages, a first electrode facing the first gas passage, and the second In the solid oxide fuel cell including the second electrode facing the gas flow path of
Single or plural first gas flow paths, single or plural second gas flow paths, first electrode, second electrode, first electrode provided at end of gas flow path of first electrode All of the first electrodes electrically connected to one of the parts of the solid oxide fuel cell comprising the terminal and the second electrode terminal provided on the side opposite to the first electrode terminal , All the second electrodes connected to each other, the first gas channel facing the first electrode, the second gas channel facing the second electrode, and the first electrode electrically The first electrode terminal connected to one and the second electrode terminal electrically connected to the second electrode as one unit of electrochemical cell, and a plurality of the electrochemical cells are juxtaposed on the same plane And the solid electrolyte materials of the plurality of electrochemical cells are not separated from each other to form an integral structure,
Two electrochemical cells adjacent to each other in juxtaposition are electrically connected to either the first electrode terminal or the second electrode terminal, and a plurality of electrochemical cells are connected in series. Fuel cell. 2. The fuel cell according to claim 1, wherein the unit electrochemical cell has a plurality of first gas flow paths and a plurality of second gas flow paths.

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