JPH0364857A - Porous electrode structure - Google Patents

Abstract

PURPOSE:To ensure good gas permeability and to decrease electric resistance by patterning a specified geometrical shape and installing a layer conductive pattern in a porous electrode. CONSTITUTION:A porous electrode structure 40 has a porous electrode 21, which forms reaction parts and a current collecting pattern 31 which is patterned in the porous electrode 21 so as to have united layer relation. Even if the porous electrode 21 is densely structured and is thinned to increase gas permeability, attendant electric resistance is practically decreased by the conductive current collection pattern 31, because the reaction parts increase in number or total area. Effective resistance of the porous electrode structure 40 when conductive leads 23 are connected to an outside circuit is decrease seeing from outside circuit. High gas permeability and low electric resistance which are antinomic are achieved without any contradiction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to structural improvements in porous electrodes required in fuel cells, gas sensors, alkali metal thermoelectric conversion devices, and the like.

[Prior Art] As mentioned above, fuel cells, gas senna, alkali metal thermoelectric conversion devices (AMTEC)
Metal Thermoelectric Conv
erter) etc., a so-called porous electrode is essential due to its principle of operation, but this porous electrode is also subject to at least some conditions that must be met.

For example, in addition to being chemically and physically stable in the usage atmosphere, it is said that the lower the electrical resistance, the better.
Furthermore, it is also required to have good air permeability so that reaction gas or generated gas can be easily supplied and released.

Among these, the chemical and physical stability of porous electrodes is sufficiently satisfactory even with existing materials, and is not a particular problem. The basic operating mechanism, both good and bad, will be briefly explained with reference to Figure 5.6.

The liquid sodium 13 supplied by the electromagnetic pump 15 is heated from 900K to about 1300K in the high temperature section 16. At this temperature, the vapor pressure of sodium is 3. O
It becomes from about 2.6 x 10'Pa to about 2.6 x 10'Pa. On the other hand, the sodium ions (Na'') that have passed through the solid electrolyte 11 are neutralized at the porous electrode 21, evaporated in vacuum, and condensed in the low temperature section 17 of about 300K to 400K. The vapor pressure of sodium is 1.Ox
10'Pa to 1. It becomes about Ox 10'Pa.

The Na'' ions in the solid electrolyte 11 are driven from the high temperature side to the low temperature side by the vapor pressure difference, that is, the concentration difference, and are then circulated back to the high temperature side by the pump 15. Electrons generated at the high-temperature side interface of the electrolyte 11 reach the porous electrode 2 via the external load 8 connected between the porous electrode 21 and the liquid sodium, so there is a potential difference between both ends of the external load 18. In other words, power can be given to the load 18.

This phenomenon can be explained in more detail by referring to the phenomenon around the porous electrode schematically shown in FIG.

In the illustrated case, the solid electrolyte 1111 is exemplified by β°°-aluminum, which is often used in this type of field, and the liquid sodium 13 passes through this solid electrolyte 1111 as Na+ ions. When it comes into contact with the porous electrode 21, it receives electrons, and what was previously ionized as Na becomes Na and vaporizes, passing through the porous electrode and heading towards the condensing surface 17, where it is ionized again. , liquefied.

The condensation surface 17 can be considered as a part of the heat dissipation section 17 in FIG. 5, but in any case, the above reaction is Na'+e →N
a ・・・・・・■ Therefore, if leads are provided on the porous electrode 21 and liquid sodium 13 sides, and the load 18 is connected between them, the electron reflux path will be closed and the current or Electric power can be extracted.

In view of such thermoelectric conversion operation, all of the conditions required of the porous electrode 21 are reasonable, as described above. For example, if the porous electrode 21 cannot be expected to have a sufficiently low resistance and the resistance is quite large, it is obvious that the flow of electrons will deteriorate and the reaction efficiency will decrease. When considering the extraction of electrical energy, that is, the flow of current, it is clear that power loss occurs in this porous electrode 21 portion.

Furthermore, if the air permeability or porosity of the porous electrode 21 is not very good and the passage of the sodium vapor 14 is poor, this also causes a reduction in the conversion efficiency per unit time.

Therefore, in the past, various attempts have been made regarding the structure of this porous electrode 21.

Figure 7 shows the conventional multi-hole power purchase f! In the first place, this type of porous electrode 21 is formed by depositing a suitable metal such as molybdenum (Mo) on the solid electrolyte 11 by sputtering or the like. Therefore, by varying the sputtering conditions, not only the film thickness but also the internal structure of the porous electrode 21 to be formed can be varied.

For example, FIG. 7(A) shows a conventional example in which the porous through hole 8i21 is formed so that the constituent particle diameter is relatively coarse.

In such a case, in Figures 5 and 6, sodium vapor 1
4, but generally it is also simply referred to as gas 14, so that the explanation is common to all devices of this type.
The passage of the gas becomes better.

In this field, the portion 22 where the solid electrolyte member 11 and the porous electrode 21 are directly connected is particularly referred to as a "three-phase interface portion." This comes from the meaning of the part where the liquid phase, solid phase, and gas phase all intersect, but specifically, it is the part where the solid electrolyte member 11, the porous electrode 21, and the gas 14 all intersect.

On the other hand, FIG. 7(B) shows a case where the diameter of each particle constituting the porous electrode 21 is made smaller and more dense. The in-plane resistance or electrical resistance value in the lead extraction direction can be reduced.

Expanding this further, as shown in Figure 7tc),
In this case, a porous electrode 21 is first sputtered to an appropriate thickness around a solid electrolyte member 11 shown in the shape of a hollow pipe, and then a lead 23 is mechanically wrapped around it an appropriate number of times. There is.

It is also common to form the solid electrolyte member 21 into a hollow pipe shape as shown in the figure, especially in AMTEC, etc., and the liquid medium is passed through this hollow part, and the gas is passed from the tube wall of the solid electrolyte member to the porous hole. However, in any case, this Fig. 7 (C)
If you adopt the electrode structure shown in
A portion 24 of the lead 23 that is wrapped around the porous electrode 21 functions as a current collector 24 and helps reduce the electrical resistance value in the lead extraction direction.

For the same purpose, as shown in FIG. 7(D) and FIG. 7(E) which is a cross-sectional view thereof, a porous electrode 21 formed on a hollow pipe-shaped solid electrolyte member 11 is shown.
On the other hand, there is also a device in which a current collecting member 25 made of conductive wires assembled in a net shape is mechanically covered, and the leads 23 are taken out from appropriate positions at both ends in the axial direction.

On the other hand, although it is also for reducing electrical resistance,
Some attempts have been made to shorten the current bus by reducing the area of individual porous electrodes, and to increase the electromotive voltage value by electrically connecting a plurality of these individual electrodes in series.

FIG. 7(F) shows such a case, which is a technique found in fuel cells.

That is, in order to allow gas to pass through, porous electrodes 2L+, 21-i, . A solid electrolyte member 2LI is formed on the film.
, 2L2. After forming the current collector electrodes 2LI, 2L2, . By forming...
A so-called unit cell 3 on the support substrate 26 in the in-plane direction
A plurality of 0-1, 30-2, . . . are formed in an integrated manner.

Then, between the two adjacent cells 30-1 and 3L2, the porous electrode 21-1 of one cell 30-1 is electrically connected to the current collecting electrode 28-7 of the other cell 21-2. Therefore, an internal built-in wiring path 2 called an ink connector
9 to increase the series combined electromotive voltage of these series integrated circuits.

[Problems to be Solved by the Invention] However, the various contrivances for conventional porous electrodes all have advantages and disadvantages, and have never been fully satisfactory.

Looking at each individual, first of all, as shown in Figure 7 (A), a porous electrode with relatively large individual particle diameters and a sparse structure allows gas to pass through easily, but As explained above, since it is not possible to increase the number of three-phase interface parts 22, which are the parts where the reaction actually occurs, or the effective reaction area, which is the total sum of them, the reaction resistance increases and the gas flow is reduced. Although it is good, the reaction efficiency does not increase, and the electrical resistance does not decrease because of the sparse structure.

On the other hand, as shown in Figure 7(B), if the particle size is made smaller and a denser structure is obtained, the porous electrode 2
Although the electrical resistance as 1 is reduced and the number of three-phase interface parts or the effective reaction area is increased, this also does not necessarily lead to an improvement in efficiency because it becomes difficult for the gas itself to pass through.

Also, in both cases of Figure 7 (^) and (B), if the purpose is simply to reduce electrical resistance,
Naturally, the thicker the film thickness of the porous electrode, the more
Electrical resistance also decreases, but this makes the passage of gas even worse, and the porosity itself may be lost.

On the other hand, Fig. 7 (C), (D), (E)
As shown in FIG. 2, mechanically winding a lead 24 or a mesh conductive member 25 made of a suitable conductive wire material onto the original porous electrode 21 for generating a reaction region (three-phase interface region). When assembled and used as a current collector, the effective electrical resistance can be kept at a relatively low value even if the porous electrode 21 is thinned to improve gas passage and reduce the reaction resistance. , it's not a bad idea at all.

However, the fatal drawback of this approach is that it is extremely unreliable from the standpoint of providing a practical device.

In other words, devices using this type of porous electrode, including the AMTEC mentioned above, are often forced to operate in high-temperature environments, so if the thermal history is repeated over a long period of time, differences in the coefficient of thermal expansion will occur. etc., and there is a high possibility that mechanical "looseness" will occur in the lead-like current collector 24 and the net-like current collector 25.Of course, if such loosening occurs, it is necessary to take the trouble to remove the current collector or the current collector. This is because the meaning that was established will be lost.

On the other hand, the conventional example shown in Fig. 7 (F) has a relatively reliable electrode structure once it is made, but because the structure is complex, the fabrication itself is extremely troublesome. Yes, and it's expensive.

Furthermore, since a plurality of unit cells are connected in series, a high voltage can be obtained, but the current capacity that can be taken out and, by extension, the output power capacity cannot be large.

Furthermore, integrating a plurality of cells and connecting them with the ink connector 29 means that this connecting part also requires an occupied area, and therefore, the more cells are integrated, the more the reaction is affected. This increases the area of the connecting portion that cannot be connected, and ultimately reduces the effective electrode area of the total area exposed to the reaction gas.

The present invention has been made in view of such conventional circumstances, and as can be understood from the above, two elements that are inherently contradictory, namely, good breathability. Another object of the present invention is to provide a porous electrode structure that can consistently satisfy the requirements of ensuring porosity and reducing electrical resistance, can withstand long-term use, and is unlikely to cause defects due to its mechanical structure. It is.

[Means for Solving the Problems] In the present invention, in order to achieve the above object, a predetermined geometrical structure is provided on one side of a porous electrode as an electrode for actually generating a reaction part such as a three-phase interface part. We propose a porous electrode structure in which a conductive current collecting pattern is patterned according to a typical shape, and the porous electrode and the patterned current collecting pattern are integrally laminated with each other.

On top of that, it is proposed that the current collection pattern should preferably also have porous properties, and further, between the porous electrode and the current collection pattern, the current collection pattern physically presses,
Structures are also presented in which a conductive current collecting member is mechanically wrapped or wrapped around a porous electrode.

On the other hand, in the present invention, as mentioned above, at least
Since it is sufficient that the porous electrode and the patterned current collection pattern are in an integral stacked relationship with each other, either side may be on top.

That is, the porous electrode is formed on one side of the support member or the solid electrolyte member, and the current collection pattern is patterned on the side of the porous electrode opposite to the side where the porous electrode is in contact with the support member or the solid electrolyte member. Alternatively, the current collection pattern may be formed on the support member or the solid electrolyte member first, and the porous electrode may be formed on top of the supporting member or solid electrolyte member. The pattern may be formed so as to be sandwiched between the porous electrode and the support member or the solid electrolyte member. Although the former is common in realizing the present invention, the latter also has extremely useful value in some cases, as will be described later.

[Function] The porous electrode structure constructed according to the present invention functions extremely advantageously in device systems such as gas sensors, fuel cells, and AMTEC.

First, in the porous electrode structure of the present invention, unlike the conventional structure which is simply composed of porous electrodes, the porous electrode structure is designed to actually control reaction areas such as three-phase interfaces. Since the porous electrode has a current collection pattern that is preferably formed in a laminated relationship, as mentioned above, for example, in order to increase the number of reaction parts or the total area, the porous electrode can be formed into a dense structure. Even if it is made thin to improve gas passage, the electrical resistance value that increases along with it is 1. It can be effectively reduced by a conductive current collection pattern.

That is, electrical connection to the external circuit can be made by connecting a conductive lead end to the external circuit to a part of the current collection pattern newly provided according to the present invention,
In this state, conversely, the effective resistance value of the wood porous electrode structure viewed from the external circuit side can be made sufficiently low. In short, it is possible to consistently satisfy both the air permeability (or porosity) and low electrical resistance of porous electrodes, which have conventionally been contradictory factors.

Of course, the geometric pattern shape of the conductive current collection pattern itself is, in principle, a matter of arbitrary design; for example, a vertical grid with intervals, a horizontal grid, or a large mesh. In addition to the above, there are various other possibilities, but if porosity cannot be expected in this current collection pattern, in order to minimize the reduction in the effective reaction area, it is possible to suppress the electrical resistance value to a sufficiently low value. It is desirable that the current collection pattern C has a shape with a wide window portion that exposes as much of the porous electrode as possible.

However, according to another proposal of the present invention, if the current collecting pattern is also made porous, it is possible to allow the gas to pass through the current collecting pattern itself, even if the area covered by the porous electrode is large. The porous electrode part underneath can also be effectively used as a part for generating reaction parts.
The pattern shape of the current collection pattern may have a somewhat wide total area.

However, in principle, any known and existing appropriate method can be used for patterning the conductive current collection pattern, and therefore, the method itself is not directly defined by the present invention, but for example, sputtering, etc. It is easy and reliable to pattern a current collecting pattern by thermal spraying or baking (sintering) on the surface of a porous electrode formed by a method. When such patterning method C is followed, as described above, it is determined whether or not the current collecting pattern itself has porosity by controlling the film thickness of the current collecting pattern. I can do it.

For example, if a pattern shape is adopted that does not have porosity, but rather widens the exposed portion of the porous electrode underneath, the film thickness can be increased to further reduce the electrical resistance value. On the other hand, if you are concerned about reducing the effective area involved in the reaction in a porous electrode, reduce the thickness of the current collection pattern to ensure good porosity. By allowing gas to pass through, it is possible to generate reaction regions even in the porous electrode portion located below the current collection pattern.

In any case, according to the porous electrode structure of the present invention, the effective electrical resistance value can be reduced sufficiently effectively compared to the conventional example which does not have any means for reducing the effective electrical resistance value other than the porous electrode. On the other hand, compared to the conventional case where a lead wire or a conductive member woven into a mesh is simply fitted onto a porous electrode, the thermal spraying method described above is A membrane member constructed using a sintering method or other so-called patterning method has good compatibility with the underlying membrane member, and even if there is a slight difference in thermal expansion coefficient between them,
It is possible to sufficiently absorb this stress and prevent deformation and peeling. However, it goes without saying that it is most preferable to select a current collection pattern material that is compatible with the porous electrode material under the condition that high conductivity can be maintained.

However, the present invention also proposes a structure in which a conductive member is mechanically wound or fitted around the porous electrode.

In other words, as mentioned above, the reliability of the electrically conductive member mechanically provided to the porous electrode alone is significantly inferior when assembled as a device, but the most basic aspect of the present invention described above Based on the disclosed results, a current collection pattern that can exhibit good adhesion to the porous electrode is provided, so it is possible to mechanically connect the lead wire on top of the porous electrode. After winding the conductive material several times or covering it with a net-like conductive member, a conductive current collection pattern of a predetermined geometric shape is patterned on top of it according to the spirit of the present invention.
The mechanically provided conductive member can be held down physically reliably, preventing loosening even if there is a slight difference in thermal expansion coefficient between the conductive member and the porous electrode. be able to.

Furthermore, the present invention also proposes a structure in which a conductive current collection pattern of a predetermined geometric shape is first formed, and then a conductive material or metal material for forming a porous electrode is formed thereon.

This structure is advantageous when the material for forming the porous electrode is a material that is easily thermally oxidized in the high temperature environment required for example in a sintering method.

In other words, if a porous electrode has been formed first and a current collection pattern is formed on it by sintering, there is a risk that the porous electrode will be thermally oxidized. If, on the contrary, the current collecting pattern is formed first and the porous electrode is formed after that, a large number of reaction parts can be generated according to the spirit of the present invention without such inconvenience. In addition, in order to reduce the effective electrical resistance of the porous electrode, which is formed to improve gas passage, and therefore has a rather high electrical resistance, The basic structure consisting of such a porous electrode and a current collecting pattern integrally laminated can be satisfied without any inconvenience.

[Example] FIG. 1 shows a porous electrode structure 4 constructed according to the present invention.
0 is shown, but in order to clearly show the comparison with the conventional example already explained with reference to FIG. 7, for example, FIG. 7(C) and FIG. 7(D) This is an improved example of the porous electrode for AMTEC shown.

Therefore, it may be a little higher than the components in the conventional example. Rather, the thermoelectric conversion by the mechanism already explained in FIGS. 5 and 6 is more important than the electrical resistance value. In forming the porous electrode, it may be formed with the main aim of allowing the reactive gas 14 such as sodium gas 14 to pass through easily and generating a large number of three-phase interface parts or reaction parts 22. Even though the constituent particles are small in size and have a dense structure, they are sufficiently thin, and the gas No. 1 is used as is.

To explain, first of all, the solid electrolyte member 11 is also in the shape of a hollow vibrator in the first embodiment of the present invention, and a porous electrode is provided on the outer peripheral surface of the solid electrolyte member 11 as in the conventional example. 2
1, for example, a molybdenum electrode 21 is deposited to a suitable thickness by sputtering.

However, in the case of the present invention, unlike the conventional example, the electrical resistance value expected for the porous power purchaser itself can be of secondary importance, and is formed by patterning.

In this first embodiment, the current collecting pattern 31 includes ring-shaped portions 32 at two positions spaced apart along the length direction or axial direction C of the hollow solid electrolyte member 11;
32, and a plurality of vertical bars 33.33.33.33.33.33.33.32. It has a vertical lattice-like geometric shape connected by..., and both portions 32 and 33 are formed on the porous electrode 21 by a thermal spraying method.

There are no restrictions in principle on the conductive material used to form the current collecting pattern 31, as long as it has the necessary conductivity and is compatible with the base electrode 21 without any problems. The same material as the porous electrode 21 may be used, but for example, if the porous conductor 8i21 is made of molybdenum (MO) as described above, the larger the area occupied by the current collection pattern 31 made of molybdenum, which is the same material, the more electrical As the resistance value decreases and, conversely, it becomes narrower, the effective area of the porous material 21 increases. Therefore, by appropriately selecting the geometrical shape set for the current collection pattern 31, and taking into consideration the number of vertical bars 33, their width, etc. in the case shown in the figure, the effective total area of the porous electrode contributing to the reaction can be increased. It is possible to realize a state that is satisfactory for both effective resistance values.

"By constructing a porous electrode structure in this way and connecting the connection lead 23 to an external circuit to an appropriate location of the current collection pattern 31, such as the ring-shaped part 32, the AMT
While ensuring sufficient number or total area of three-phase interface parts required in EC, etc., and ensuring good porosity for good gas passage, it is still effective as seen from the external circuit side. Low electrical resistance can be achieved.

As is clear, if the thickness of the laminated layer formed on the porous electrode 21 is kept to about 100 μm or less, the current collection pattern itself can be expected to have fairly good porosity.

In other words, it becomes a porous current collection pattern 31.

In such a case, each part of the porous electrode 21 that is covered by the current collection pattern 31 and located below it is never disturbed by the current collection pattern, and the reaction area is covered with the current collection pattern 31 in the same way as other parts. It can be used as it is as a part for generation, and since a new current collecting pattern is laminated according to the present invention, the effective area of the porous electrode is not reduced.

On the other hand, the thickness of the current collection pattern 31 formed by thermal spraying is 10 μm.
If the thickness is reduced below a certain level, the porosity increases, but the effect of reducing the effective resistance of the porous electrode 21 becomes weaker. In other words,
Even when considering porosity, there is an optimal design range for the thickness of the current collecting pattern 31, so patterning can be done by thermal spraying, sintering, or other existing thin film forming techniques. When forming a film, the particle structure within the film can be varied to be dense or dense with good controllability depending on the formation conditions, and this fact can be effectively utilized in the present invention.

Of course, as mentioned earlier, by devising the geometry of the current collection pattern 31, the effective resistance value of the porous electrode can be sufficiently reduced, but the total area occupied by the porous electrode does not have to be very large. In such a case, there is no necessity to require the current collection pattern 31 to be porous; in other words,
The illustrated ring-shaped portion 32 and vertical bar 33 are made sufficiently thin, and by making them even thicker,
It is also possible to design a design in which the "window" portion surrounded by the crosspieces is widened to increase the effective area of the porous electrode 21 while at the same time greatly reducing the resistance value.

Furthermore, although this is not a limitation on the present invention, when general β゛°°-alumina is used for the solid electrolyte 11, the porous electrode 21 may be made of sputtering method, not limited to molybdenum. It is desirable to form it by This is because the compatibility between the two is good, the adhesive strength is quite high, and a large number of three-phase interfaces can be generated. For example, if this porous electricity purchaser FJ21 is also formed by a thermal spraying method, it will not be possible to obtain as good adhesion as the sputtering method, and the number of three-phase interfaces will not be large.

On the other hand, as mentioned above, the current collecting pattern 31 formed by thermal spraying is mechanically and electrically compatible with molybdenum electrodes formed by sputtering, and has high adhesion. Showing good o, ivy contact. As can be understood from the above, using a suitable manufacturing method for the porous electrode 21 and the current collection pattern 31 is, in a sense, a skill in realizing the porous electrode structure of the present invention. .

In addition, the method for creating the porous electrode 21 in place of the sputtering method is as follows:
The same applies to other embodiments of the present invention described below. Therefore, in each of the examples described below, only characteristic modified portions will be explained.

FIG. 2 shows a case in which the predetermined pattern shape of the current collecting pattern 31 is formed into a horizontal lattice pattern, as an example showing that the predetermined pattern shape can be designed quite arbitrarily.

In fact, it is possible to form a porous electrode film that has good porosity and has a high three-phase J-plane generation function.
Moreover, it has good mechanical and electrical compatibility with the current collecting pattern 31 formed by thermal spraying or sintering. however,
Molybdenum porous electrode 21 is formed by sputtering or CVD method.
Even if it is formed, it is desirable that the film thickness be sufficiently thinner than in the past, and generally only about several micrometers, in order to satisfy the purpose of the present invention.

Above, the first embodiment of the present invention has been described in detail in accordance with FIG. A pair of vertical bars 33 33 are connected to the circuit connection leads 23 , 23 and are diametrically opposed and connect the pair of ring-shaped portions 32 , 32 .
However, between the vertical bars 33 and 33, a horizontal bar is provided that extends circumferentially on the surface of the porous electrode while maintaining an appropriate relationship in the axial direction with respect to the ring-shaped portions 32 and 32. 34. ... are provided, and the current collection pattern 31 as a whole has a horizontal grid shape.

Naturally, this porous electrode structure 40 also has the following functions:
Since it is the same as the first embodiment described above, its explanation will be omitted, but considering it as an example of geometrical modification, it can be inferred from these first and second embodiments that it is roughly vertical bars and horizontal bars. Various other shapes can be assumed, including a square lattice shape in which the shapes coexist.

On the other hand, the third embodiment shown in the third figure also uses a conductive member 35 mechanically fitted onto the surface of the porous electrode 21.

That is, in the case shown in the figure, after the conductive member 35, which is made by braiding a suitable conductive wire material into a net shape, is placed on the porous electrode 21 as tightly as possible, thermal spraying or baking is performed by a method.
A current collection pattern 31 consisting only of ring-shaped portions 32.degree. 32 is patterned so as to suppress both axial end portions of the net-like conductive member 35 from above.

Even in this case, the current collecting pattern 31 adopted according to the present invention can be integrally laminated and exhibit good physical adhesion to the porous electrode 21 below, so that By sandwiching both end portions between the current collecting pattern 31 or its ring-shaped portion 32 and the porous electrode 21, the conductive member 35 can be prevented from loosening.

Of course, if necessary, the number of ring-shaped parts 32 that suppress the conductive member 35 may be increased, but in any case, in the case of this embodiment, the geometric pattern of the net-like conductive member 35 and the wire material used are By appropriately considering the type, diameter, etc., the necessary resistance value reduction effect can be obtained.

In the drawings, the dimensional relationships in each embodiment are exaggerated to make it easier to understand the structure itself, so it is difficult to understand, but in reality, the mesh of the conductive member 35 is The size can be made larger than in the first and second embodiments.

This is because, as mentioned earlier, when forming a lattice shape entirely by patterning, the thickness of the current collection pattern 31 is generally on the order of sub-millimeter, whereas when the conductive wire is woven or Although not shown in Figure 7 (C
) When winding the porous electrode 21 in a spiral manner around the surface thereof according to the method shown in the conventional example,
This is because the diameter of the conductive wire used can be made to the order of magnitude, and the effective resistance value along the current path can be reduced accordingly.

However, essentially, as in the first and second embodiments, if there are no mechanical assembly parts at all, the reliability of the device can be alleviated. It is best to think of it as an example.

However, in all of the embodiments described above, the porous electrode 21 is first formed on the solid electric field layer 11, and then the current collection pattern 31 is formed by patterning.

However, depending on the combination of materials used for the porous electrode 21 and the current collection pattern 31 and the method used to form them, the porous electrode 21, which serves as the base electrode for creating the current collection pattern, may deteriorate. If a current collection pattern made of nickel or platinum is formed on a porous electrode formed by sputtering using a sintering method instead of the thermal spraying method described above,
Due to the extremely high temperature and atmosphere during the sintering process, the molybdenum in the underlying layer was sometimes oxidized.

Therefore, in the present invention, we also consider measures for such cases, and
An embodiment represented by the structure shown in FIG. 4 is also proposed.

That is, as seen in this example, the solid electrolyte 1
First, a current collecting pattern 31 made of nickel material is patterned on top of the current collecting pattern 31 using a sintering method or the like according to a predetermined pattern shape. Then, if a molybdenum film is formed in a relatively low temperature and high vacuum environment by sputtering, for example, to form the porous electrode 21, no damage will be caused to the porous electrode.

In practice, by using such measures, the nickel film created by the sintering method exhibits fairly good porosity, and the reduction in the effective area of the porous electrode 21 can be effectively suppressed. .

Thermal theory, the above-mentioned material relationship between nickel and molybdenum is not limited, and the point is, as seen in the fourth illustrated embodiment, according to the present invention, which one is made first, the porous electrode or the current collecting pattern? This means that there is now room for choice depending on the materials used and the forming method.

Further, in the illustrated embodiments, a solid electric field resistor 11 is shown as a physical support substrate or support member for the porous electrode 21, but in the conventional example shown in FIG. may be viewed as simply indicating a physical support member. This is a matter of choice depending on what kind of device the present invention is applied to.

Naturally, the spatial shape (three-dimensional shape) of the supporting member 11 is arbitrary, and it may be in the shape of a hollow vibrator or a flat plate. Also when creating the porous electrode structure 40, the solid electrolyte 11 can have any three-dimensional shape.

[Effects] According to the present invention, gas sensors, fuel cells, AMTEC
For various device systems that require porous electrodes, the number and total area of reaction parts that can be formed is sufficient, gas flow is good, and the effective electrical resistance value is sufficiently low. A porous electrode structure can be provided.

Moreover, the structure and manufacturing procedure are not complicated, and it is mechanically extremely durable, with high reliability that can withstand long-term use.

Therefore, the present invention will greatly contribute to this type of field in the future.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a first embodiment of a porous electrode structure constructed according to the present invention. FIG. 2 is a schematic configuration diagram of a second embodiment in which the pattern shape of the current collection pattern is changed. FIG. 3 is a schematic configuration diagram of a third embodiment that also uses a mechanically assembled conductive member. FIG. 4 is a schematic diagram of an embodiment in which the order of formation of the porous electrode and current collection pattern is reversed. FIG. 5 is an explanatory diagram regarding the principle operation of an alkali metal thermoelectric conversion device as an example of a device that can use the porous electrode structure of the present invention. FIG. 6 is an explanatory diagram of phenomena occurring around a porous electrode due to thermoelectric conversion. FIG. 7 is an explanatory diagram of various structural examples of conventional porous electrodes. In the figure, 11 is a supporting member or a solid electrolyte member, 21 is a porous electrode, 22 is a three-phase interface part or a reaction part, 31 is a current collection pattern, 35 is a mechanically created conductive member, and 40 is the whole The porous electrode structure of the present invention. Figure 1 Figure 2 Figure 6 Figure 3 Figure 4

Claims (5)

[Claims] (1) A porous electrode characterized by having a conductive current collecting pattern on one side of the porous electrode that is patterned according to a predetermined geometric shape and has an integral laminated relationship with the porous electrode. structure. The porous electrode structure according to claim (1), characterized in that (2) the current collection pattern also has porosity; (3) A conductive current collecting member is provided between the porous electrode and the current collecting pattern, which is physically pressed by the current collecting pattern and mechanically wrapped or covered around the porous electrode. The porous electrode structure according to claim 1 or 2, characterized in that: (4) The porous electrode is formed on one surface of the support member or solid electrolyte member, and the current collection pattern is on the surface opposite to the surface where the porous electrode is in contact with the support member or solid electrolyte member. The porous electrode structure according to claim 1 or 2, wherein the porous electrode structure is formed by patterning. (5) the porous electrode is formed on one surface of the support member or the solid electrolyte member, and the current collection pattern is formed between the porous electrode and the support member or the solid electrolyte member; The porous electrode structure according to claim (1) or (2).