JP7548107B2 - Electrochemical cells and photosynthetic apparatus - Google Patents

Description

The present invention relates to an electrochemical cell and a photosynthetic device.

Conventionally, electrochemical cells are known that include a housing, an electrode pair disposed inside the housing, and an electrolyte that is placed inside the housing so as to fill the space between the electrode pair. Such electrochemical cells generate an electrochemical reaction by applying a voltage between the electrode pair.

For example, Patent Document 1 discloses an electrochemical cell including an electrode for oxidation reaction, an electrode for reduction reaction, an electrolyte filled between the electrode for oxidation reaction and the electrode for reduction reaction, and a frame material that supports the electrode for oxidation reaction and the electrode for reduction reaction in an opposing position. Patent Document 2 discloses an electrochemical cell including an electrode, a ring-shaped counter electrode arranged opposite the electrode, and an electrolyte filled between the electrode and the counter electrode.

JP 2019-189929 A JP 2018-9879 A

It is possible to use a metal case as the case for the electrochemical cell. For example, when considering using an electrochemical cell outdoors, the weather resistance (meaning resistance to changes in weather, e.g., resistance to deformation, discoloration, deterioration, and other changes caused by the effects of sunlight, ultraviolet rays, temperature changes, etc.) of the electrochemical cell case can be an issue, so in order to improve the weather resistance of the case, it is possible to use a metal case for the case. Patent Document 1 does not mention the weather resistance of the electrochemical cell, but it does state that the frame may be made of metal.

On the other hand, there is a demand to be able to visually check the state inside the housing of an electrochemical cell (for example, the state of the electrochemical reaction) from outside the housing. When the housing is made of resin, the inside can be visually checked from outside the housing by forming the housing from a transparent resin material. However, when the housing is made of metal, it becomes impossible to visually check the inside from outside the housing.

One solution is to provide an optical window in the metal housing to allow the interior to be viewed. Patent Document 2 shows that an observation window (optical window) is provided in the housing of an electrochemical cell. In particular, the optical window in Patent Document 2 is located beyond the electrode via the counter electrode (on an extension line connecting the electrode and counter electrode), and allows the surface of the electrode to be observed through the ring-shaped counter electrode.

Here, unlike the electrochemical cell of Patent Document 2, when the electrode pair is plate-shaped, it is particularly desirable to be able to view the opposing portions of the electrode pair from the side, i.e., from a direction parallel to the extension direction of the electrodes. When the electrode pair is plate-shaped, only one of the electrodes in the electrode pair can be seen when viewing the inside of the housing from a direction perpendicular to the extension direction of the electrodes. This can result in problems such as the opposing portions of the electrode pair being difficult to see, making it difficult to properly view the electrochemical reaction between the electrode pair.

The object of the present invention is to make it possible to easily view the opposing portions of a plate-shaped oxidation electrode and a plate-shaped reduction electrode in an electrochemical cell having a metal housing.

The present invention is an electrochemical cell in which a water oxidizing reaction and a carbon dioxide reducing reaction occur by applying a voltage between a pair of electrodes and supplying water and carbon dioxide, the electrochemical cell comprising: a metal casing made of metal , the metal casing having an insulating lining on its inner surface ; a plate-shaped oxidation electrode including a member having an oxidation catalytic function and a plate-shaped reduction electrode including a member having a reduction catalytic function, which are installed opposite each other within the metal casing; an electrolyte filled between the oxidation electrode and the reduction electrode; an optical window fixed to the metal casing by a bolt inserted from the inside of the metal casing into a bolt hole provided in the metal casing, the optical window being transparent and provided in a direction parallel to the extension direction of the oxidation electrode or the reduction electrode from a portion facing the oxidation electrode and the reduction electrode; a washer provided between the inner surface of the metal casing and a head of the bolt; a first bolt hole sealing member provided between the inner surface of the metal casing and the washer; and a second bolt hole sealing member provided between the washer and the head of the bolt .

Preferably, the device further comprises a cover member attached to the outer surface of the metal housing so as to cover the edge of the optical window.

Preferably, the device further comprises an optical window seal member provided between the outer surface of the metal housing and the optical window.

Preferably, the optical window is made of glass, resin, or quartz.

Preferably, multiple pairs of the oxidation electrode and the reduction electrode are arranged in the metal housing so that their opposing surfaces are parallel to each other.

The present invention also provides a photosynthetic device comprising the electrochemical cell according to any one of claims 1 to 6 and a solar cell connected between the oxidizing electrode and the reducing electrode, wherein a voltage is applied between the oxidizing electrode and the reducing electrode by the solar cell.

According to the present invention, in an electrochemical cell having a metal housing, the opposing portions of a plate-shaped oxidation electrode and a plate-shaped reduction electrode can be easily viewed.

FIG. 2 is an exploded perspective view of the large-scale photosynthetic device according to the present embodiment. FIG. 2 is a cross-sectional view of a large-scale photosynthetic device according to the present embodiment. FIG. 2 is a top side view of an electrochemical cell according to the present embodiment. FIG. 2 is a cross-sectional view of an optical window and its surrounding area. FIG. 2 is a diagram showing the state inside the housing as seen through an optical window when no electrochemical reaction is occurring. FIG. 2 is a diagram showing the state inside the housing as seen through an optical window when an electrochemical reaction is occurring.

1 is an exploded perspective view of a large-scale photosynthetic device 1 according to this embodiment. FIG. 2 is a YZ cross-sectional view of the large-scale photosynthetic device 1. The large-scale photosynthetic device 1 includes an electrochemical cell 10 and a solar cell 24. In the drawings of this specification, the width direction of the large-scale photosynthetic device 1 is the X-axis, the depth direction is the Y-axis, and the height direction is the Z-axis. The positive side of the X-axis may be called the left side, the negative side of the X-axis may be called the right side, the positive side of the Y-axis may be called the rear side, the negative side of the Y-axis may be called the front side, the positive side of the Z-axis may be called the upper side, and the negative side of the Z-axis may be called the lower side. The electrochemical cell 10 includes a hollow housing 12 with a sealed internal space, an oxidation electrode 14 including a member having an oxidation catalyst function and a reduction electrode 16 including a member having a reduction catalyst function, both of which are arranged in the housing 12, and an electrolyte 18 (see FIG. 2) filled in the housing 12, particularly between the oxidation electrode 14 and the reduction electrode 16.

The electrochemical cell 10 applies a voltage between the oxidizing electrode 14 and the reducing electrode 16, which causes an electrochemical reaction between the oxidizing electrode 14 and the reducing electrode 16 via the electrolyte 18 to produce a predetermined substance. In this embodiment, the oxidizing electrode 14 is a Ti (titanium) substrate on whose surface IrOx nanocolloids are supported as a member having an oxidation catalyst function, the reducing electrode 16 is a Ti substrate on whose surface Ru complex polymer (RuCP) and a carbon carrier are supported as a member having a reduction catalyst function, and the electrolyte 18 is a potassium phosphate buffer solution in which carbon dioxide is dissolved. As a result, water is oxidized and carbon dioxide is reduced by the electrochemical reaction in the electrochemical cell 10 to produce formic acid. Note that the oxidizing electrode 14, the reducing electrode 16, and the electrolyte 18 are not limited to the above. For example, the substrate for the oxidation electrode 14 and the reduction electrode 16 may be a Ti substrate or a glass substrate with a transparent conductive film having a metal conductive line such as Ag (e.g., a fluorine-doped SnO2 film (FTO) substrate). A protective layer of glass or resin may be formed on the Ag conductive line.

The oxidation electrode 14 and the reduction electrode 16 are plate-shaped members and are arranged opposite each other. In this embodiment, the oxidation electrode 14 and the reduction electrode 16 are arranged in the housing 12 with their extension direction parallel to the XZ plane. The oxidation electrode 14 and the reduction electrode 16 in this embodiment are large electrodes. Specifically, the oxidation electrode 14 and the reduction electrode 16 are approximately 1 m (meter) x 1 m in size.

In this embodiment, multiple pairs of oxidation electrodes 14 and reduction electrodes 16 are arranged in the housing 12. More specifically, multiple pairs of oxidation electrodes 14 and reduction electrodes 16 are arranged in the housing 12 so that their opposing surfaces are parallel. Specifically, as shown in FIG. 2, multiple oxidation electrodes 14 and multiple reduction electrodes 16 standing parallel to the XZ plane are arranged in the Y-axis direction so that they are staggered. Multiple pairs of oxidation electrodes 14 and reduction electrodes 16 whose opposing surfaces are parallel to the XZ plane are arranged in the Y-axis direction. In this case, a member having an oxidation or reduction catalytic function is supported on both sides of the substrate of the oxidation electrodes 14 and reduction electrodes 16.

The large-scale photosynthetic device 1 according to this embodiment is configured to include a solar cell 24. The solar cell 24 is attached to the outer surface (front surface) of one side of the housing 12 (more specifically, the lid portion 22 of the housing 12 described later). As shown in FIG. 2, the solar cell 24 is connected between the oxidation electrode 14 and the reduction electrode 16, and a voltage generated by irradiating the solar cell 24 with light is applied to the oxidation electrode 14 and the reduction electrode 16. In this way, the large-scale photosynthetic device 1 according to this embodiment generates a predetermined substance by causing an electrochemical reaction with sunlight. Note that the wiring (solid line) from the solar cell 24 to the oxidation electrode 14 and the wiring (dotted line) from the solar cell 24 to the reduction electrode 16 in FIG. 2 are merely conceptual diagrams of wiring, and wires are not actually laid out in this manner.

The housing 12 has a generally rectangular parallelepiped, i.e., box-shaped, interior space for containing the oxidation electrode 14, reduction electrode 16, and electrolyte 18. As described above, in this embodiment, the housing 12 is necessarily large in size because it needs to accommodate multiple large oxidation electrodes 14 and reduction electrodes 16. The width (length in the left-right direction) and height of the housing 12 are at least 1 m or more. Therefore, it can be said that the electrochemical cell 10 according to this embodiment is a large electrochemical cell that is significantly larger in size than conventional electrochemical cells.

In this embodiment, the housing 12 includes a container portion 20 having an opening 20a and a lid portion 22 that closes the opening 20a. The lid portion 22 is attached to the container portion 20 to form a housing 12 with a sealed internal space. Specifically, the container portion 20 includes a rear wall 20b extending in the XZ plane, a plurality of side walls 20c erected forward from each side of the rear wall 20b, and a flange portion 20d extending outward from the side walls 20c so as to surround the opening 20a. The opening 20a opens forward. In addition, the flange portion 20d is provided with a plurality of bolt holes 30 aligned along the circumferential direction. In addition, the lid portion 22 is also provided with a plurality of bolt holes 32 aligned along its outer edge. The lid 22 is brought into contact with the container 20 (specifically, the flange 20d) so that the bolt holes 30 and 32 are aligned, and bolts 34 (see FIG. 2) are inserted through the bolt holes 30 and 32, thereby sealing the container 20 and the lid 22 together to form the housing 12. If the sealing member 36 described below is not provided, the bolts 34, the bolt holes 30 and 32, and the grooves along the circumferential direction of the flange 20d may not be provided. In this case, the container 20 and the lid 22 are sealed together by bonding or welding, etc., to ensure the airtightness of the housing 12.

In this embodiment, in order to improve the airtightness between the container part 20 and the lid part 22, a seal member 36 made of elastic resin or rubber is provided on the flange part 20d of the container part 20. Specifically, a groove is formed along the circumferential direction on the front side surface of the flange part 20d, and the seal member 36 is disposed in a semi-embedded state in the groove. As a result, when the container part 20 (flange part 20d) and the lid part 22 are brought into close contact with each other, the seal member 36 is positioned between the flange part 20d and the lid part 22 to close the gap between them, thereby improving the airtightness between the container part 20 and the lid part 22, i.e., the airtightness of the housing 12.

An electrolyte supply port 38 is provided on the lower side wall 20c of the container portion 20. The electrolyte 18 is supplied from the electrolyte supply port 38 into the housing 12. An electrolyte discharge port 40 is provided on the upper part of the rear wall 20b of the container portion 20. The electrolyte 18 containing formic acid produced by the electrochemical reaction is discharged from the electrolyte discharge port 40. The discharged electrolyte 18 is collected in a tank or the like.

In this embodiment, the housing 12 is provided with a reinforcing structure for improving the rigidity of the housing 12 against the internal pressure. The internal pressure from within the housing 12 includes positive internal pressure (e.g., internal pressure due to the electrolyte 18 or gas) that applies a force from the inside to the outside of the housing 12, and negative internal pressure (internal pressure applied during degassing processing, etc.) that applies a force from the outside to the inside of the housing 12 (a force pulling inward). Positive internal pressure is sometimes called positive pressure, and negative internal pressure is sometimes called negative pressure. In this embodiment, as a reinforcing structure, structural members 42, 44 that are long in the material axis direction along the outer side surface of the housing 12 are provided on the outer surface of the housing 12. The structural members 42, 44 are preferably made of a material with high rigidity, and in this embodiment, they are made of metal. The structural members 42, 44 are attached to the housing 12 by welding. By attaching the structural members 42, 44 to the housing 12, the bending rigidity of the housing 12 in the material axis direction of the structural members 42, 44 is improved. In addition, a structural member 42 is provided on the container portion 20 of the housing 12, and a structural member 44 is provided on the lid portion 22.

The housing 12 is a metal housing made of metal. By making the housing 12 out of metal, its weather resistance is improved at least compared to when the housing 12 is made of resin. This makes it possible to use the electrochemical cell 10 outdoors. Note that since the housing 12 is made of metal, it is not transparent.

Since the electrolyte 18 is filled between the metal housing 12 (its inner surface) and the oxidation electrode 14 or reduction electrode 16, there is a risk of an unintended electrochemical reaction (side reaction) occurring between the housing 12 and the oxidation electrode 14 or reduction electrode 16. In addition, if the housing 12 is made of iron, for example, there is a risk of the housing 12 corroding when the corrosive electrolyte 18 or the liquid product produced by the electrochemical reaction comes into contact with the housing 12.

In view of this, in this embodiment, the inner surface of the metal housing 12 is lined with an insulating material. As shown in FIG. 2, the inner surface of the rear wall 20b and the side wall 20c of the container portion 20 of the housing 12 are lined to form a lining layer 50. The inner surface of the lid portion 22 is also lined to form a lining layer 52. The insulating material forming the lining layer 50 is, for example, a resin (e.g., a fluorine-based resin). Specifically, the material forming the lining layer 50 can be ETFE (ethylene tetrafluoroethylene copolymer), PFA (perfluoroalkoxyalkane), or PE (polyethylene). The lining layers 50 and 52 ensure insulation between the housing 12 and the electrolyte 18, and can suppress the electrochemical reaction between the housing 12 and the oxidation electrode 14 or the reduction electrode 16. In addition, the lining layers 50 and 52 prevent the electrolyte 18 from directly contacting the housing 12, thereby suppressing corrosion of the housing 12.

Since the housing 12 is a metal housing and is opaque, its inside cannot be seen from the outside through the housing 12. Therefore, in order to see the inside from the outside of the housing 12, a transparent optical window (not shown in Figs. 1 and 2) is attached to the housing 12. In particular, the optical window is provided in a direction parallel to the extension direction of the oxidation electrode 14 or reduction electrode 16 from the opposing portion of the oxidation electrode 14 and reduction electrode 16 so that the opposing portion of the oxidation electrode 14 and reduction electrode 16 arranged opposite each other in the housing 12 can be easily seen.

The housing 12 is provided with a window hole 60 for mounting an optical window, and a number of bolt holes 62 provided near the window hole 60. In this embodiment, the window hole 60 is circular, and the bolt holes 62 are arranged in a line along the outer periphery of the window hole 60. As described below, the optical window is mounted in the window hole 60 and then secured in place by bolts inserted through the bolt holes 62.

As described above, the optical window is provided in a direction parallel to the extension direction of the oxidation electrode 14 or reduction electrode 16 from the opposing portion of the oxidation electrode 14 and the reduction electrode 16. However, since the oxidation electrode 14 and the reduction electrode 16 extend in a direction parallel to the XZ plane, the optical window is provided on the left and right side surfaces or the top and bottom side surfaces of the housing 12. In this embodiment, the optical window is provided in the upper part of the left and right side walls 20c of the container part 20. Therefore, a window hole 60 and a plurality of bolt holes 62 are provided in the upper part of the left and right side walls 20c of the container part 20. Note that the optical window (i.e., the window hole 60 and the plurality of bolt holes 62) may be provided only in either the left or right side wall 20c, or may be provided in the upper and lower side walls 20c.

Figure 3 is a side view of the top of the electrochemical cell 10 (viewed from the right), and Figure 4 is a cross-sectional view of the optical window 70 and its surroundings. In Figure 4, the right side of the optical window 70 is the inside of the housing 12, and the left side of the optical window 70 is the outside of the housing 12. In the following description, the inside means the inside side of the housing 12, and the outside means the outside side of the housing 12.

The optical window 70 is substantially circular in plan view, and is a transparent member as described above. The optical window 70 is made of, for example, glass, resin (e.g., polycarbonate, etc.), or quartz. Quartz has high transparency and is suitable as a material for the optical window 70, but is expensive. Resin and glass have the characteristic of being less transparent than quartz, but less expensive.

As shown in FIG. 4, the diameter of the inner portion 70a of the optical window 70, which is located on the inside when attached, is smaller than the diameter of the central portion 70b, which is located on the outside of the inner portion 70a when attached. The diameter of the window hole 60 and the diameter of the inner portion 70a are approximately the same, so that the inner portion 70a fits exactly into the window hole 60. When the inner portion 70a is fitted into the window hole 60, the inner surface of the outer edge of the central portion 70b (the portion that protrudes laterally (up and down in FIG. 4) more than the inner portion 70a) abuts against the side wall 20c, restricting the inward movement of the optical window 70.

A cover member 72 that covers the edge of the optical window 70 is provided on the outer surface of the side wall 20c. As shown in Figs. 3 and 4, the cover member 72 has an approximately cylindrical shape overall and is a member formed of resin or the like. The cover member 72 has a flange portion 72a that protrudes toward the central axis of the cylindrical shape at the outer end in the attached state. In the attached state, the diameter of the outer portion 70c of the optical window 70, which is located outside the central portion 70b, is smaller than the diameter of the central portion 70b. The cover member 72 is attached so that the inner surface of the flange portion 72a of the cover member 72 abuts against the outer surface of the outer edge of the central portion 70b of the optical window 70 (the portion that protrudes laterally from the outer portion 70c), and the cover member 72 covers the edge of the optical window 70.

The cover member 72 has a plurality of bolt holes 72b arranged along the circumferential direction. After aligning the plurality of bolt holes 72b with the plurality of bolt holes 62 provided in the side wall 20c, bolts 74 are inserted into each bolt hole 62, 72b from the inside of the side wall 20c. The cover member 72 is fixed to the side wall 20c by inserting nuts 76 into each bolt 74 from the outside and tightening them. As described above, the cover member 72 covers the edge of the optical window 70, so that when the cover member 72 is fixed to the side wall 20c by the bolts 74 and nuts 76, the optical window 70 (the outer edge of the central portion 70b) is pressed against the side wall 20c, and the side wall 20c and the optical window 70 are in close contact with each other. As a result, there is no gap between the side wall 20c and the optical window 70, and the airtightness of the internal space of the housing 12 is ensured.

Here, an optical window seal member 77 may be provided between the outer surface of the housing 12 and the optical window 70. For example, as shown in FIG. 4, the optical window seal member 77 may be provided between the outer surface of the side wall 20c and the inner surface of the outer edge of the central portion 70b of the optical window 70. The optical window seal member 77 may be, for example, a resin packing, an O-ring, or a gasket. The optical window seal member 77 fills the gap between the side wall 20c and the optical window 70. This ensures that the internal space of the housing 12 is more airtight.

A bolt hole seal member 78 is provided between the inner surface of the side wall 20c and the head 74a of the bolt 74. The bolt hole seal member 78 seals the gap between the bolt hole 62 and the bolt 74 provided in the side wall 20c, thereby ensuring the airtightness of the internal space of the housing 12. In particular, the bolt hole 62 may be formed so that the area around the bolt hole 62 on the inner surface of the side wall 20c is slightly recessed (as viewed from the inside). In addition, the lining layer 50 is formed on the inner surface of the side wall 20c, and the lining layer 50 (the inner surface) may have microscopic irregularities. If the side wall 20c has a recess or the lining layer 50 has an irregularity, a gap may be formed between the bolt hole 62 and the bolt 74, which may reduce the airtightness of the internal space of the housing 12. By using the bolt hole seal member 78, even if there is a recess in the side wall 20c or unevenness is formed in the lining layer 50, the bolt hole seal member 78 absorbs the effects of these and ensures the airtightness of the internal space of the housing 12.

Specifically, the bolt hole sealing member 78 is a circular member with a hole in the center, and is made of an elastic resin such as silicone. The bolt hole sealing member 78 is placed inside the side wall 20c, and the bolt 74 is inserted into the hole in the bolt hole sealing member 78. As a result, the bolt hole sealing member 78 is fixed by the bolt 74 to close the bolt hole 62 on the inside of the side wall 20c.

In this embodiment, a round washer 80 is inserted between the side wall 20c and the head 74a of the bolt 74. Therefore, the bolt hole seal member 78 includes a first bolt hole seal member 78a between the side wall 20c and the round washer 80, and a second bolt hole seal member 78b between the round washer 80 and the head 74a.

As described above, in the electrochemical cell 10 according to this embodiment, an optical window 70 is provided in the upper part of the left and right side walls 20c of the metal housing 12, i.e., in the portion where the oxidation electrode 14 and the reduction electrode 16 face each other, in a direction parallel to the extension direction of the oxidation electrode 14 or the reduction electrode 16. This allows the inside of the housing 12 to be viewed from the outside of the housing 12 through the optical window 70. In particular, the portion where the oxidation electrode 14 and the reduction electrode 16 face each other can be viewed favorably.

Figure 5 shows the interior of the housing 12 as seen through the optical window 70 when no electrochemical reaction is occurring, and Figure 6 shows the interior of the housing 12 as seen through the optical window 70 when an electrochemical reaction is occurring.

As shown in FIG. 5, it can be seen that the opposing portions of the oxidizing electrode 14 and the reducing electrode 16 can be clearly seen through the optical window 70. In particular, when multiple oxidizing electrodes 14 and multiple reducing electrodes 16 are arranged in a row as in this embodiment, the multiple opposing portions between each oxidizing electrode 14 and each reducing electrode 16 can be clearly seen through the optical window 70. Also, as shown in FIG. 6, when an electrochemical reaction occurs, bubbles are mixed into the electrolyte 18, and it can be clearly seen that gas (e.g., oxygen) is generated by the electrochemical reaction. The flow of the electrolyte 18 can also be clearly seen.

The optical window 70 allows the electrochemical reaction in the housing 12 and the flow of the electrolyte 18 to be observed, and therefore, it is possible to quickly detect abnormalities inside the housing 12 (such as an increase in pressure loss due to precipitation in the electrolyte 18) by visual inspection before the sensor detects an abnormality in the electrochemical reaction. For example, if an abnormality inside the housing 12 can be detected by visual inspection, it is possible to take measures such as replacing the filter for the electrolyte 18 before fatal performance deterioration of the electrochemical cell 10 occurs. In addition, when the electrochemical cell 10 is applied to factory exhaust gas, there is a concern about side reactions caused by SOx (sulfur oxides) and NOx (nitrogen oxides) other than carbon dioxide that are mixed into the electrolyte 18. Before performance deterioration due to the generation of deposits generated by side reactions occurs, it is possible to maintain performance by visually checking the inside of the housing 12 through the optical window 70 and replacing the electrolyte 18 or the filter.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

1 Large photosynthetic device, 10 Electrochemical cell, 12 Housing, 14 Oxidation electrode, 16 Reduction electrode, 18 Electrolyte, 20 Container portion, 20a Opening, 20b Rear wall, 20c Side wall, 20d, 72a Flange portion, 22 Lid portion, 24 Solar cell, 30, 32 Bolt hole, 34, 74 Bolt, 36 Seal member, 38 Electrolyte supply port, 40 Electrolyte discharge port, 42, 44 Structural member, 50, 52 Lining layer, 60 Window hole, 62 Bolt hole, 70 Optical window, 70a Inner portion, 70b Center portion, 70c Outer portion, 72 Cover member, 74a Head, 76 Nut, 77 Optical window seal member, 78 Bolt hole seal member, 78a First bolt hole seal member, 78b Second bolt hole seal member, 80 Round washer.

Claims (6)

An electrochemical cell in which a reaction for oxidizing water and a reaction for reducing carbon dioxide occur by applying a voltage between an electrode pair and supplying water and carbon dioxide,
A metal housing made of metal, the metal housing having an insulating lining on an inner surface thereof ;
a plate-shaped oxidation electrode including a member having an oxidation catalytic function and a plate-shaped reduction electrode including a member having a reduction catalytic function, the plate-shaped oxidation electrode and the plate-shaped reduction electrode being disposed opposite each other in the metal housing;
an electrolyte filled between the oxidation electrode and the reduction electrode;
an optical window fixed to the metal housing by a bolt inserted from inside the metal housing into a bolt hole formed in the metal housing, the optical window being transparent and provided in a direction parallel to an extension direction of the oxidation electrode or the reduction electrode from a portion where the oxidation electrode and the reduction electrode face each other;
a washer provided between an inner surface of the metal housing and the head of the bolt;
a first bolt hole seal member provided between an inner surface of the metal housing and the washer;
a second bolt hole seal member provided between the washer and the head of the bolt;
An electrochemical cell comprising: a cover member attached to an outer surface of the metal housing so as to cover an edge of the optical window;
10. The electrochemical cell of claim 1 further comprising: a sealing member for an optical window provided between an outer surface of the metal housing and the optical window;
3. The electrochemical cell of claim 1 or 2, further comprising: The optical window is made of glass, resin, or quartz.
4. An electrochemical cell according to claim 1 , wherein the electrochemical cell is a casing. A plurality of pairs of the oxidation electrode and the reduction electrode are arranged in the metal housing such that their opposing surfaces are parallel to each other.
2. The electrochemical cell of claim 1 . An electrochemical cell according to any one of claims 1 to 5 ;
a solar cell connected between the oxidizing electrode and the reducing electrode;
Equipped with
A voltage is applied between the oxidizing electrode and the reducing electrode by the solar cell.
A photosynthetic apparatus characterized by the above-mentioned.