Electrolytic device

Abstract

To provide an electrolytic device capable of suppressing the temperature in an inner region from rising.SOLUTION: There is provided an electrolytic device 1 that comprises an electrolytic cell having an electrolytic layer, a first electrode 21, a second electrode, and a first flow channel, a second flow channel, and a flow channel forming conductor 5 that abuts on the first electrode 21 and also forms the first flow channel, and that is configured to electrolyze a reaction fluid F to produce hydrogen by applying a voltage between the first electrode 21 and the second electrode through the flow channel forming conductor 5. When viewed from a normal direction Z of a first surface, the first electrode 21 is divided into an outer peripheral region A1 including an outer peripheral end of the first electrode 21 and an inner region A2 inside the outer peripheral region A1, the outer shape of the inner region A2 being similar to that of the first electrode 21 and the area of the inner region A2 being half of that of the first electrode 21. Furthermore, the electrolytic cell has a larger average value of endothermic density in the inner region A2 than in the outer peripheral region A1, the endothermic density being an endothermic energy amount per unit area associated with an electrolysis reaction of the electrolytic cell.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrolysis device. [Background technology]

[0002] In an electrochemical cell stack constituting a fuel cell, hydrogen generation device, or the like, electrodes are provided on one side and the other side of an electrolyte layer. For example, in a fuel cell, fuel is supplied to one electrode, and an electrochemical reaction occurs at the electrode to generate electricity. In the fuel cell described in Patent Document 1, a metal plate with a plurality of openings supports the one electrode side of the cell, and fuel is supplied to the electrode through the openings. Furthermore, the opening density (i.e., the opening ratio) is uniform across the entire surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,972,161 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in an electrolysis device that generates hydrogen by electrolyzing a reaction fluid, there is a problem that the temperature near the center of the cell may become too high. That is, as the supplied current density increases, Joule heat increases. Furthermore, since heat generated in the inner region of the cell is difficult to dissipate to the surroundings, there is a concern that the temperature of the inner region may rise too high. Thus, there is a problem that the temperature of the inner region may become too high compared to the peripheral region in the electrolysis device.

[0005] The present invention has been made in view of the above problem, and aims to provide an electrolysis device capable of suppressing a temperature rise in the inner region. [Means for solving the problem]

[0006] One aspect of the present invention is an electrolytic cell (2) including an electrolyte layer (20), a first electrode (21) provided on a first surface of the electrolyte layer, and a second electrode (22) provided on a second surface of the electrolyte layer opposite to the first surface; a first flow path (3) facing the first electrode; a second flow path (4) facing the second electrode; a flow path forming conductor (5) that contacts the first electrode and forms the first flow path, An electrolysis device (1) configured to generate hydrogen by electrolyzing a reaction fluid (F) that flows through the first flow path and is supplied to the first electrode by applying a voltage between the first electrode and the second electrode via the flow path forming conductor, When viewed from a normal direction (Z) of the first surface, the first electrode is divided into an outer circumferential region (A1) including an outer circumferential edge of the first electrode and an inner region (A2) inside the outer circumferential region, the outer shape of the inner region is similar to the outer shape of the first electrode, and the area of ​​the inner region is half the area of ​​the first electrode; When the amount of heat absorbed per unit area accompanying the electrolysis reaction in the electrolytic cell is defined as the endothermic density, The electrolysis device has a higher average endothermic density in the inner region than in the outer circumferential region. [Effects of the Invention]

[0007] In the electrolysis device of the above aspect, the average value of the endothermic heat density in the inner region is greater than the average value of the endothermic heat density in the outer circumferential region, thereby making it possible to suppress a temperature rise in the inner region.

[0008] As described above, according to the above aspect, it is possible to provide an electrolysis device that can suppress a temperature rise in the inner region. In addition, the symbols in parentheses in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view illustrating a portion of the electrolysis device according to the first embodiment. [Figure 2] 4 is a plan view of a partition plate of a flow path forming conductor as viewed from the Z direction, showing an outer peripheral region and an inner region in the first embodiment. FIG. [Figure 3] FIG. 2 is a diagram showing an outline of the relationship between the current density supplied to the electrolytic cell and the amount of heat generated by the electrolytic cell in the first embodiment. [Figure 4] 3 is a diagram showing the distribution of current density, Joule heat, and reaction heat during operation of the electrolysis cell in the first embodiment. FIG. [Figure 5] 4 is a plan view of a partition plate of a flow path forming conductor as viewed from the Z direction, showing a central region and a side region in the first embodiment. FIG. [Figure 6] 4 is a plan view of a partition plate of a flow path forming conductor as viewed from the Z direction, showing an upstream region, a midstream region, and a downstream region in the first embodiment. FIG. [Figure 7] 4 is a plan view of a partition plate of a flow path forming conductor as viewed from the Z direction, showing an outer peripheral region, a first inner region, and a second inner region in the first embodiment. FIG. [Figure 8] FIG. 11 is a plan view of a partition plate of a flow path forming conductor, seen from the Z direction, showing an outer peripheral region and an inner region in the second embodiment. [Figure 9] FIG. 10 is a plan view of a partition plate of a flow path forming conductor as viewed from the Z direction in the comparative example 1. [Figure 10] 1 is a contour diagram of the temperature distribution in the electrolysis device of Comparative Example 1, analyzed in Experimental Example 1. [Figure 11] 10 is a contour diagram of the temperature distribution in the electrolysis device of Embodiment 2, analyzed in Experimental Example 1. FIG. [Figure 12] 12 is a diagram showing the distribution of each physical quantity along the dashed line L1 shown in FIGS. 10 and 11, analyzed in Experimental Example 1. FIG. [Figure 13] 12 is a diagram showing the distribution of each physical quantity along the dashed line L2 shown in FIGS. 10 and 11, analyzed in Experimental Example 1. FIG. [Figure 14]FIG. 11 is a plan view of a flow path forming conductor, seen from the Z direction, showing an outer peripheral region and an inner region in the third embodiment. [Figure 15] FIG. 11 is a plan view of a partition plate of a flow path forming conductor, seen from the Z direction, showing an outer peripheral region and an inner region in the fourth embodiment. [Figure 16] 16 is a cross-sectional explanatory view of a flow path-forming conductor and a first electrode, taken along line XVI-XVI in FIG. 15. FIG. [Figure 17] FIG. 13 is a plan view of a flow path forming conductor, seen from the Z direction, showing an outer peripheral region and an inner region in the fifth embodiment. [Figure 18] FIG. 13 is a cross-sectional explanatory view of a flow path forming conductor and a first electrode in a sixth embodiment. [Figure 19] FIG. 13 is a cross-sectional explanatory view of a flow path forming conductor and a first electrode in a seventh embodiment. [Figure 20] FIG. 13 is a cross-sectional explanatory view of a flow path forming conductor and a first electrode in an eighth embodiment. [Figure 21] FIG. 20 is a cross-sectional explanatory view of a flow path forming conductor and a first electrode in a modified example of the eighth embodiment. [Figure 22] FIG. 13 is a cross-sectional explanatory view of a flow path forming conductor and a first electrode in a ninth embodiment. [Figure 23] FIG. 20 is a plan view of a flow path forming conductor seen from the Z direction, showing an outer circumferential region, an inner region, an upstream region, a midstream region, and a downstream region in the tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment 1) An embodiment of the electrolysis device will be described with reference to FIGS. 1, the electrolysis device 1 of this embodiment includes an electrolysis cell 2, a first flow path 3, a second flow path 4, and a flow path-forming conductor 5. The electrolysis cell 2 includes an electrolyte layer 20, a first electrode 21, and a second electrode 22.

[0011] The first electrode 21 is provided on a first surface 201 of the electrolyte layer 20. The second electrode 22 is provided on a second surface 202 opposite the first surface 201 of the electrolyte layer 20. The first flow path 3 faces the first electrode 21. The second flow path 4 faces the second electrode 22. The flow path forming conductor 5 abuts the first electrode 21 and forms the first flow path 3.

[0012] The electrolysis device 1 is configured to electrolyze a reaction fluid F to generate hydrogen (H2) by applying a voltage between a first electrode 21 and a second electrode 22 via a flow path forming conductor 5. The reaction fluid F flows through the first flow path 3 and is supplied to the first electrode 21.

[0013] 2, when the first electrode 21 is divided into an outer peripheral region A1 and an inner region A2, the average value of the endothermic heat density in the inner region A2 is greater than the average value of the endothermic heat density in the outer peripheral region A1. For example, the average value of the endothermic heat density in the inner region A2 is preferably 1.1 times or more the average value of the endothermic heat density in the outer peripheral region A1.

[0014] Here, the outer peripheral region A1 and the inner region A2 are regions into which the first electrode 21 is divided as follows. As shown in FIG. 2, when viewed from the normal direction Z of the first surface 201, the first electrode 21 is divided into an outer peripheral region A1 that includes the outer peripheral edge of the first electrode 21, and an inner region A2 that is inside the outer peripheral region A1. The outer shape of the inner region A2 is similar to the outer shape of the first electrode 21, and the area of ​​the inner region A2 is half the area of ​​the first electrode 21. Furthermore, the inner region A2 includes the geometric center of gravity of the first electrode 21. In this embodiment, the geometric center of gravity of the outer peripheral region A1 and the geometric center of gravity of the inner region A2 coincide with each other.

[0015] Furthermore, the "endothermic density" is defined as the amount of heat absorbed per unit area associated with the electrolysis reaction in the electrolytic cell 2. Furthermore, the "average endothermic density" refers to the average endothermic density in each region. For example, the average endothermic density in the outer peripheral region A1 is defined as the total amount of heat absorbed in the outer peripheral region A1 divided by the area of ​​the outer peripheral region A1.

[0016] The flow path forming conductor 5 has a partition plate 51 that separates the first flow path 3 and the first electrode 21. As shown in FIGS. 1 and 2, the partition plate 51 has a plurality of openings 31 formed therein. The flow path forming conductor 5 including the partition plate 51 is made of a metal material. The first flow path 3 faces the first electrode 21 via the partition plate 51. As shown in FIG. 1, the reactant fluid F in the first flow path 3 is configured to be supplied to the first electrode 21 via the plurality of openings 31 formed in the partition plate 51. Note that FIG. 1 is a schematic diagram showing a cross section of a portion of the electrolysis device 1.

[0017] As shown in FIG. 1 , the second flow path 4 is formed between the second electrode 22 and a separator 50 facing it. The separator 50 forms the first flow path 3 facing the other electrolytic cells. In this embodiment, the flow path-forming conductor 5 forming the first flow path 3 includes a separator 50 and a partition plate 51. A current collector 23 is disposed on the second electrode 22 of the electrolytic cell 2. That is, the current collector 23 is disposed in the second flow path 4. The second electrode 22 and the separator 50 disposed opposite the second electrode 22 are electrically connected via the current collector 23. The flow path-forming conductor 5, the electrolytic cell 2, and the second flow path 4 are repeatedly stacked in this order to form an electrolytic cell stack. Note that the separator 50 shown in FIG. 1 is also part of the flow path-forming conductor stacked on the upper side of the electrolytic cell 2 shown in the same figure.

[0018] The stacking direction is the same as the normal direction Z of the first surface 201 of the electrolyte layer 20, and this direction will also be referred to as the Z direction as appropriate. The flow direction of the reaction fluid F in the first flow path 3, which is perpendicular to the Z direction, will also be referred to as the X direction as appropriate. Note that the flow of the reaction fluid F may be directed in various directions locally, but the overall flow direction will be referred to as the X direction. The direction perpendicular to both the X direction and the Z direction will also be referred to as the Y direction as appropriate.

[0019] End plates (not shown) are arranged on both ends of the above-described electrolysis cell stack in the stacking direction, i.e., in the Z direction, and sandwich this stacked structure from the Z direction. Fig. 1 is a schematic explanatory diagram showing a part of the electrolysis cell stack in the stacking direction in a cross section perpendicular to the Y direction.

[0020] The electrolysis device 1 of this embodiment may be, for example, an electrolysis device using an SOEC (i.e., a solid oxide electrolysis cell). That is, the electrolyte layer 20 in the electrolysis cell 2 may be made of a solid oxide such as yttria-stabilized zirconia.

[0021] The electrolysis device 1 generates hydrogen by electrolyzing a reactive fluid F such as water vapor (H2O). By applying a voltage between the first electrode 21 and the second electrode 22, the first electrode 21, which serves as a hydrogen electrode, generates a hydrogen gas containing H2O+2e - →H2+O 2- As a result, hydrogen (H2) is produced at the first electrode 21, and as shown in Fig. 4, the hydrogen is discharged downstream together with the reaction fluid F through the first flow path 3. The dashed arrow i shown in Fig. 4 represents a current.

[0022] In addition, in the second electrode 22 as an oxygen electrode, O 2- →1 / 2O2+2e - An electrode reaction occurs. Oxygen ions move through the electrolyte layer 20 from the first electrode 21 side to the second electrode 22 side. Then, oxygen generated at the second electrode 22 flows as an oxygen-containing gas through the second flow path 4. A carrier gas can be flowed through the second flow path 4, and in this case, the oxygen gas generated at the second electrode 22 is diluted by the carrier gas and flows through the second flow path 4 as an oxygen-containing gas, and is discharged. As the carrier gas, for example, air can be used.

[0023] The electrode reaction at the first electrode 21 described above is an endothermic reaction. Therefore, as the amount of reactive fluid supplied to the first electrode 21 increases, the amount of heat absorbed by the electrode reaction increases. As the electrode reaction becomes more active, the current density increases. However, as the current density increases, Joule heat at the first electrode 21 also increases. Therefore, when Joule heat and reaction endothermic heat are taken into consideration, as shown in FIG. 3, when the current density becomes higher than a predetermined value (thermal neutral point M), the overall heat generation increases.

[0024] FIG. 3 shows an outline of the relationship between the current density and the amount of heat generated and the amount of heat absorbed in the electrolytic cell 2. The vertical axis represents the amount of heat generated, and the negative side (below the horizontal axis in the graph) represents endothermia. The horizontal axis represents the current density. As described above, when the electrolysis device 1 is in operation, heat absorption due to the electrode reaction and Joule heat due to the current are mainly generated. When the current density is relatively low, the amount of heat absorbed is greater than the Joule heat, so the electrolytic cell 2 absorbs heat and no temperature rise occurs. On the other hand, when the current density is increased above the thermal neutral point M, the Joule heat exceeds the amount of heat absorbed, the electrolytic cell 2 generates heat, and the temperature rises. The current density at which the amount of heat generated and the amount of heat absorbed are equivalent is the thermal neutral point M.

[0025] In recent years, there has been a demand for increasing the current density during operation of the electrolysis device 1 in order to reduce the size of the electrolysis device 1 and improve hydrogen productivity. Increasing the current density leads to the problem of temperature rise, as described above. Here, the outer peripheral region A1 (see FIG. 2 ) of the electrolysis cell 2 is relatively susceptible to heat dissipation to the surroundings, but the inner region A2 is relatively difficult to dissipate heat. Therefore, when the electrolysis device 1 is operated at a high current density, the temperature is particularly likely to rise in the inner region A2.

[0026] Therefore, the inventors of the present application discovered that by making the average value of the endothermic density in the inner region A2 higher than the average value of the endothermic density in the outer peripheral region A1, it is possible to suppress the temperature rise in the inner region A2 while enabling the electrolysis device 1 to operate at a high current density overall.

[0027] In this embodiment, the arrangement of the opening holes 31 in the flow path forming conductor 5 is devised in order to make the average value of the heat absorption density in the inner region A2 higher than the average value of the heat absorption density in the outer peripheral region A1.

[0028] The electrode reaction in the first electrode 21 described above is an endothermic reaction. Therefore, when a large amount of reactant fluid F is supplied to the first electrode 21, the amount of heat absorbed increases. Therefore, as shown in FIG. 4, the endothermic reaction is active in the portion of the first electrode 21 facing the center of the opening 31, and the amount of heat absorbed is likely to increase. On the other hand, in the portion of the first electrode 21 facing the portion of the partition plate 51 other than the opening 31, a certain amount of current used in the electrolytic reaction flows, generating Joule heat.

[0029] Therefore, in the electrolysis device 1 having the openings 31 provided in the partition plate 51, the current density differs between the positions where the openings 31 are provided and other positions, resulting in different amounts of heat generation (heat absorption). For example, it is possible to supply power so that the position facing the center of the openings 31 becomes an operating point (P1 in FIG. 3) where the current density is lower than the thermal neutral point M, and the position facing the positions other than the openings 31 on the partition plate 51 becomes an operating point (P2 in FIG. 3) where the current density is higher than the thermal neutral point M.

[0030] Based on the above-mentioned concept, it is believed that increasing the aperture ratio of the opening holes 31 in a predetermined region can suppress a temperature rise in that region. Therefore, in this embodiment, as described above, in order to suppress a temperature rise in the inner region A2, the aperture ratio of the opening holes 31 in the inner region A2 is increased as shown in Fig. 2. For example, it is preferable that the aperture ratio in the inner region A2 is 1.1 times or more the aperture ratio in the outer peripheral region A1.

[0031] Naturally, no current flows through the openings 31 in the flow path-forming conductor 5. Therefore, as shown in Fig. 4, the current density tends to be low at the position of the first electrode 21 facing the openings 31, particularly at the position facing the center of the openings 31. Therefore, the Joule heat generated tends to be low at the position of the first electrode 21 facing the center of the openings 31 compared to other positions. In other words, the heat absorption is high and the heat generation is low at the position of the first electrode 21 facing the center of the openings 31.

[0032] Furthermore, the current density tends to be high at the position of the first electrode 21 facing the outer periphery of the opening hole 31, and Joule heat tends to be generated. As described above, this is thought to be because the electrode reaction is active at the position of the first electrode 21 facing the opening hole 31, and the current density of the current flowing through the flow path forming conductor 5 to this position increases.

[0033] In the graph of reaction heat in Fig. 4, the reaction heat is positive in the areas where the openings 31 are not formed. This is because the heat generated by the overvoltage during the electrode reaction exceeds the heat absorption. In other words, the graph of reaction heat in Fig. 4 shows the heat generated by the overvoltage together with the heat of the pure endothermic reaction.

[0034] As described above, in this embodiment, as shown in FIG. 2, the aperture ratio of the plurality of opening holes 31 is set higher in the inner region A2 than in the outer peripheral region A1. That is, when viewed from the Z direction, the aperture ratio of the plurality of opening holes 31 is set differently among the plurality of regions (A1, A2). This creates a difference in the average values ​​of heat absorption density among the plurality of regions. That is, by making the average value of heat absorption density in the outer peripheral region A1 higher than the average value of heat absorption density in the inner region A2, the temperature rise in the inner region A2 is effectively suppressed. This makes it possible to suppress the temperature rise in the inner region A2. The aperture ratio of the opening holes 31 is the opening area per unit area of ​​the partition plate 51, and is the value obtained by dividing the total opening area of ​​the plurality of opening holes 31 in each region by the area of ​​each region.

[0035] As mentioned above, "between multiple regions" means "between the outer peripheral region A1 and the inner region A2," and can also mean "between the central region B2 and the lateral regions B1, B3," "between the upstream region C1, the midstream region C2, and the downstream region C3," and "between the first inner region A21 and the second inner region A22," as described below.

[0036] 5 , when viewed from the Z direction, the electrolysis device 1 of this embodiment is configured so that the average endothermic heat density differs for each region when the first electrode 21 is divided into three equal parts in the width direction Y, which is perpendicular to the flow path direction X of the first flow path 3. That is, the first electrode 21 is divided into a central region B2 and two side regions B1 and B3 that sandwich the central region B2 in the width direction Y. In this case, the average endothermic heat density in the central region B2 is greater than the average endothermic heat density in the side regions B1 and B3. For example, the average endothermic heat density in the central region B2 is preferably 1.1 times or more the average endothermic heat density in the side regions B1 and B3.

[0037] 5, in this embodiment, the aperture ratio of the openings 31 in the central region B2 is higher than the aperture ratios of the openings 31 in the side regions B1 and B3. This increases the average heat absorption density in the central region B2. This configuration suppresses temperature rise in the central region B2, where heat is relatively difficult to dissipate.

[0038] 6, when viewed from the Z direction, the first electrode 21 is divided into three equal parts in the flow path direction Y of the first flow path 3, that is, into an upstream region C1, a midstream region C2, and a downstream region C3, and the average value of the endothermic density is also made different for each region. That is, the average value of the endothermic density in the midstream region C2 is greater than the average value of the endothermic density in the upstream region C1 and the average value of the endothermic density in the downstream region C3. For example, the average value of the endothermic density in the midstream region C2 is preferably 1.1 times or more the average value of the endothermic density in the upstream region C1 and the average value of the endothermic density in the downstream region C3.

[0039] 6, the aperture ratio of the openings 31 in the midstream region C2 is higher than the aperture ratio of the openings 31 in the upstream region C1 and higher than the aperture ratio of the openings 31 in the downstream region C3. This increases the average value of the heat absorption density in the midstream region B2. This configuration suppresses the temperature rise in the central region B2, where heat is relatively difficult to dissipate.

[0040] In this embodiment, when the inner region A2 is further divided into a first inner region A21 and a second inner region A22 as shown in Fig. 7, the average value of the endothermic density in the first inner region A21 is greater than the average value of the endothermic density in the second inner region A22. Here, the first inner region A21 and the second inner region A22 have similar outer shapes and are equivalent in area. The second inner region A22 is a region surrounding the first inner region A21. For example, the average value of the endothermic density in the first inner region A21 is preferably 1.1 times or more the average value of the endothermic density in the second inner region A22.

[0041] To achieve this, in this embodiment, the plurality of openings 31 are formed so that the opening ratio of the openings 31 in the first inner region A21 is greater than the opening ratio of the openings 31 in the second inner region A22.

[0042] In this way, when the inner region A2 (see FIG. 2 ) is further divided into the two regions as described above and the average values ​​of the endothermic densities are compared, the average value of the endothermic density is higher in the first inner region A21, which is closer to the center of the electrolytic cell 2. Furthermore, from a macroscopic perspective, the average value of the endothermic density is configured to be higher toward the center of the electrolytic cell 2. This makes it even easier to suppress local temperature increases in the electrolytic cell 2.

[0043] As described above, according to this embodiment, it is possible to provide an electrolysis device capable of suppressing a temperature rise in the inner region.

[0044] (Embodiment 2) In this embodiment, as shown in FIG. 8, the shape of the opening hole 31 provided in the partition plate 51 of the flow path forming conductor 5 is rectangular. More specifically, the opening 31 has a substantially square shape.

[0045] In this embodiment, similarly to the first embodiment, when the first electrode 21 is divided into an outer peripheral region A1 and an inner region A2, the outer peripheral region A1 has a larger aperture ratio of the aperture holes 31 than the inner region A2. Furthermore, when the inner region A2 is divided into a first inner region A21 and a second inner region A22 (see FIG. 7), the first inner region A21 has a larger aperture ratio of the aperture holes 31 than the second inner region A22.

[0046] Furthermore, when the first electrode 21 is divided into a central region B2 and two side regions B1 and B3 (see FIG. 5), the central region B2 has a larger aperture ratio of the openings 31 than the side regions B1 and B2. Furthermore, when the first electrode 21 is divided into an upstream region C1, a midstream region C2, and a downstream region C3 (see FIG. 6), the midstream region C2 has a larger aperture ratio of the openings 31 than the upstream region C1 and the downstream region C3.

[0047] Other aspects are the same as in embodiment 1. Note that, of the symbols used in embodiment 2 and onwards, the same symbols as those used in the previous embodiments represent the same components as in the previous embodiments, unless otherwise specified. This embodiment also achieves the same effects as embodiment 1.

[0048] (Comparative form 1) 9, in this embodiment, the openings 31 of the flow path forming conductor 5 are provided uniformly over the entire first electrode 21. In this embodiment, a plurality of openings 31 of the same size and shape are formed at equal intervals in both the X and Y directions. Other than the arrangement of the openings 31, etc., it is the same as in the first embodiment.

[0049] When the openings 31 are arranged as in this embodiment, no particular bias occurs in the heat absorption density across the entire first electrode 21. This raises concerns about a temperature rise in the inner region A2 where heat dissipation is difficult.

[0050] (Experimental Example 1) In this example, the temperature distribution in the electrolytic cell 2 of the electrolytic device 1 of the above-described second embodiment and the electrolytic device of comparative embodiment 1 were analyzed and compared. The temperature distribution was analyzed using CAE (Computer Aided Engineering). The analysis was performed under the condition that the average current density exceeded the thermal neutral point M, and the current density at the position facing the center of the opening hole 31 was less than the thermal neutral point M.

[0051] First, contour diagrams of temperature distribution obtained by CAE are shown in Figs. 10 and 11. Fig. 10 shows the analysis results for the electrolysis apparatus of Comparative Example 1, and Fig. 11 shows the analysis results for the electrolysis apparatus of Embodiment 2. In each diagram, the darker the area, the higher the temperature. In both analysis results, it can be seen that the temperature rise at the position corresponding to the opening hole 31 is suppressed compared to the surrounding area. This is consistent with the above-mentioned consideration that the endothermic reaction is promoted at the position facing the opening hole 31, suppressing the temperature rise.

[0052] Comparing the analysis results for Comparative Form 1 ( FIG. 10 ) with those for Embodiment 2 ( FIG. 11 ), the following can be clearly stated. That is, as can be seen from FIG. 10 , the temperature of the inner region A2 is high in the electrolysis device of Comparative Form 1. In contrast, as shown in FIG. 11 , the temperature rise in the inner region A2 is relatively suppressed in the electrolysis device of Embodiment 2. This can be said to be because the electrolysis device of Embodiment 2 has a high aperture ratio of the opening holes 31 in the inner region A2, which suppresses the temperature rise in the inner region A2.

[0053] Fig. 12 shows graphs of the distributions of temperature, Joule heat, electrochemical reaction heat, and current density along dashed line L1 parallel to the X direction shown in Fig. 10 and Fig. 11, respectively. Fig. 13 shows graphs of the distributions of temperature, Joule heat, electrochemical reaction heat, and current density along dashed line L2 parallel to the Y direction shown in Fig. 10 and Fig. 11, respectively. In each of the graphs shown in Fig. 12 and Fig. 13, dashed curves indicate the distribution of each physical quantity for the electrolysis device of Comparative Form 1, and solid curves indicate the distribution of each physical quantity for the electrolysis device of Embodiment 2.

[0054] As can be seen from Fig. 12, first, in terms of temperature distribution, the temperature rise near the center is suppressed in the second embodiment compared to the first comparative embodiment. Furthermore, in terms of electrochemical reaction heat, the analysis results for the second embodiment show that the amount of heat absorption is particularly large at the position corresponding to the central opening 31. This is thought to be because the opening 31 near the center is enlarged in the second embodiment, resulting in a large amount of heat absorption. By enlarging the opening 31 near the center (inner region A2) in this way and increasing the amount of heat absorption at that location, the temperature rise around the opening 31 is also suppressed. As a result, the temperature rise in the inner region A2 is suppressed, as shown in the temperature distribution graph in Fig. 12.

[0055] 12, the temperature peak is slightly shifted downstream of the flow of the reaction fluid, i.e., to the right side of the graph, which is thought to be due to the heat in the center of the electrolytic cell 2 being transported slightly downstream by the flow of the reaction fluid.

[0056] Similarly, as can be seen from Fig. 13, in the temperature distribution in the Y direction, the temperature rise near the center is suppressed in the second embodiment compared to the first comparative embodiment. Also, with regard to the heat of electrochemical reaction, the analysis results for the second embodiment show that the amount of heat absorption at the position corresponding to the opening hole 31 near the center in the Y direction is large. These are generally similar to the temperature distribution and heat absorption amount distribution in the X direction (see Fig. 12). However, the graphs in Fig. 13 are all generally symmetrical.

[0057] (Embodiment 3) In the electrolysis device 1 of this embodiment, as shown in Fig. 14, the number density of the opening holes 31 provided in the flow path forming conductor 5 is made different among the plurality of regions. As a result, the efficiency of the opening holes 31 is made different among the plurality of regions.

[0058] In this embodiment, the plurality of opening holes 31 have the same area. In the first embodiment, as shown in Fig. 2, a plurality of types of opening holes 31 having different areas are provided, but in this embodiment, the plurality of opening holes 31 have the same area. In addition, the number density of the opening holes 31 is changed between the outer peripheral region A1 and the inner region A2 to provide a difference in the aperture ratio. Here, the number density means the number of opening holes 31 formed per unit area.

[0059] That is, the number density of the opening holes 31 in the inner region A2 is made higher than the number density of the opening holes 31 in the outer peripheral region A1. In other words, the formation pitch of the opening holes 31 in the inner region A2 is made narrower than the formation pitch of the opening holes 31 in the outer peripheral region A1. In addition, in this embodiment, the shapes of the multiple opening holes 31 are also made the same. The rest is the same as in the first embodiment.

[0060] In this embodiment, the areas of the openings 31 are set to be equal to each other. This reduces the difference in the amount of reaction fluid F supplied to the positions of the first electrode 21 facing the openings 31. This makes it possible to prevent the current flowing around the openings 31 from becoming locally large. As a result, it is easy to prevent Joule heat from being generated significantly around a specific opening 31. In addition, the same effects as those of the first embodiment are achieved.

[0061] (Embodiment 4) In this embodiment, as shown in FIGS. 15 and 16, the flow path forming conductor 5 has a plurality of protrusions 53 that come into contact with the first electrode 21. In the embodiment shown in FIG. 15, the occupancy rate of the plurality of protrusions 53 is made different among the plurality of regions (A1, A2), thereby creating a difference in the average value of the endothermic density among the plurality of regions.

[0062] In this embodiment, the flow path forming conductor 5 includes a substrate portion 52 and a plurality of protrusions 53. The protrusions 53 have their protruding ends in contact with the first electrode 21. As a result, a first flow path 3 is formed between the substrate portion 52 and the first electrode 21 and between the plurality of protrusions 53.

[0063] In the flow path forming conductor 5 having such a configuration, as shown in Fig. 15, the plurality of protrusions 53 are formed so that the occupancy rate of the protrusions 53 is higher in the outer peripheral region A1 than in the inner region A2. For example, the occupancy rate of the protrusions 53 in the outer peripheral region A1 is preferably 1.1 times or more the occupancy rate of the protrusions 53 in the inner region A2. The occupancy rate of the protrusions 53 is obtained as the occupancy area of ​​the protrusions 53 per unit area when viewed from the Z direction. For example, the occupancy rate of the protrusions 53 in the outer peripheral region A1 is the value obtained by dividing the area of ​​the protrusions 53 in the outer peripheral region A1 by the area of ​​the outer peripheral region A1.

[0064] In this embodiment, the area of ​​each protrusion 53 when viewed from the Z direction is different between the outer peripheral region A1 and the inner region A2. That is, the projected area in the Z direction of the protrusion 53 in the outer peripheral region A1 is larger than the projected area in the Z direction of the protrusion 53 in the inner region A2. The rest is the same as in the first embodiment.

[0065] In this embodiment, the occupancy rate of the protrusions 53 in the inner region A2 is relatively small, so that the average value of the heat absorption density in the inner region A2 can be increased, thereby suppressing the temperature rise in the inner region A2. In addition, the same effects as those of the first embodiment are achieved.

[0066] (Embodiment 5) In this embodiment, as shown in FIG. 17, the areas of the plurality of protrusions 53 as viewed from the Z direction are made equal to each other. In addition, the number density of the protrusions 53 is changed between the outer peripheral region A1 and the inner region A2 to provide a difference in the occupancy rate of the protrusions 53. That is, the number density of the protrusions 53 in the inner region A2 is made higher than the number density of the protrusions 53 in the outer peripheral region A1. In addition, in this embodiment, the shapes of the multiple protrusions 53 are also made the same. The rest is the same as in the fourth embodiment.

[0067] In this embodiment, the occupancy rate of the protrusions 53 in the inner region A2 is relatively small, so that the average value of the heat absorption density in the inner region A2 can be increased, thereby suppressing the temperature rise in the inner region A2. In addition, the same effects as those of the fourth embodiment are achieved.

[0068] (Embodiment 6) 18, in this embodiment, the height of the first flow path 3 is made different among a plurality of regions (A1, A2), thereby making a difference in the average value of the endothermic density among the plurality of regions.

[0069] The height of the first flow path 3 refers to the height in the Z direction. In this embodiment, the first flow path 3 has a portion having a height h1 and a portion having a height h2 that is higher than h1. The portion having the height h2 is provided in the inner region A2. In the outer peripheral region A1, the height of the first flow path 3 is h1.

[0070] In other words, the average height of the first flow paths 3 in the inner region A2 is higher than the average height of the first flow paths 3 in the outer peripheral region A1. The average height of the first flow paths 3 in the inner region A2 is preferably 1.1 times or more the average height of the first flow paths 3 in the outer peripheral region A1. The rest is the same as in the first embodiment.

[0071] (Embodiment 7) As shown in FIG. 19, this embodiment is a modification of the sixth embodiment (FIG. 18). That is, in this embodiment, similarly to the fourth embodiment, the flow path forming conductor 5 is composed of the substrate portion 52 and the protrusion portion 53. In addition, the average height of the first flow paths 3 in the inner region A2 is higher than the average height of the first flow paths 3 in the outer circumferential region A1.

[0072] In this embodiment, the first flow path 3 has a portion having a height h1, a portion having a height h2 that is higher than h1, and a portion having a height h3 that is even higher than h2. A portion having a height h2 is provided more inward than the portion having height h1, and a portion having a height h3 is provided more inward than the portion having height h2. Other aspects are the same as in embodiment 6. This embodiment also has the same effects as embodiment 6.

[0073] (Embodiment 8) In this embodiment, as shown in FIG. 20, the thickness of the first electrode 21 is varied depending on the position, thereby varying the heat absorption density depending on the position. The first electrode 21 is formed so that the height position of the surface on the first flow path 3 side varies depending on the position in the X direction and the position in the Y direction. The height of the first flow path 3 increases in the areas where the thickness of the first electrode 21 is reduced. This increases the flow rate of the reaction fluid flowing through the first flow path 3, thereby accelerating the endothermic reaction.

[0074] In this embodiment, the thickness of the first electrode 21 is made greater in the inner region A2 than in the outer circumferential region A1. This makes it possible to absorb a greater amount of heat in the inner region A2 than in the outer circumferential region A1. In particular, in the embodiment shown in Fig. 20, the surface of the first electrode 21 on the side of the first flow path 3 is formed in a tapered shape so that the thickness of the first electrode 21 gradually decreases toward the center of the first electrode 21.

[0075] For example, as shown in FIG. 21, the surface of the first electrode 21 facing the first flow path 3 may be formed in a stepped shape so that the thickness of the first electrode 21 gradually decreases toward the center of the first electrode 21. In addition, the configuration and effects are the same as those of the fourth embodiment.

[0076] (Embodiment 9) In this embodiment, the porosity of the first electrode 21 is made different among a plurality of regions, as shown in Fig. 22. This provides a difference in the average value of the endothermic density among the plurality of regions. As described above, the first electrode 21 is made of a porous electrode material. The porosity of this porous electrode varies depending on the position. The porosity of the entire outer peripheral region A1 is higher than the porosity of the entire inner region A2. For example, the porosity of the entire outer peripheral region A1 is preferably 1.1 times or more the porosity of the entire inner region A2.

[0077] In this embodiment, the first electrode 21 has a low-porosity portion 213 with a relatively low porosity and a high-porosity portion 214 with a relatively high porosity. The high-porosity portion 214 is provided in the inner region A2. The entire outer peripheral region A1 of the first electrode 21 is made up of the low-porosity portion 213. However, the arrangement of the high-porosity portion 214 and the low-porosity portion 213 is not limited to this. For example, the first electrode 21 may be configured so that the porosity gradually increases toward the inside.

[0078] This allows a larger amount of reaction fluid to be supplied to the inner region A2 of the first electrode 21, thereby increasing the amount of heat absorbed in the inner region A2, thereby suppressing a temperature rise in the inner region A2. In addition, the configuration and effects are the same as those of the first embodiment.

[0079] (Embodiment 10) In this embodiment, as shown in FIG. 23, the average value of the endothermic density in the downstream region C3 is set higher than the average value of the endothermic density in the upstream region C1. In this embodiment, the occupancy rate of the openings 31 is set to be higher in the downstream region C3 than in the upstream region C1.

[0080] As in the previous embodiment, the average endothermic density is higher in the inner region A2 than in the outer circumferential region A1. However, as shown in the analysis results of Experimental Example 1 described above, in a configuration in which the opening holes 31 are evenly arranged, such as in Comparative Example 1, the temperature peak is slightly shifted downstream of the flow of the reaction fluid from the center. In accordance with this temperature distribution, the position where the endothermic density is high is shifted slightly downstream from the center in this embodiment. Other than that, the configuration and effects are the same as those of the first embodiment.

[0081] Among the above-described embodiments, a plurality of the embodiments may be appropriately combined to form an embodiment. In addition to the case where the first electrode 21 is divided into the outer peripheral region A1 and the inner region A2 (see FIG. 2), the first embodiment has also shown that a predetermined difference in endothermic density occurs in each of the plurality of regions even when the first electrode 21 is divided in the following other ways.

[0082] That is, the other division methods include dividing the first electrode 21 into a central region B2 and side regions B1 and B3 (see FIG. 5), into an upstream region C1, a midstream region C2 and a downstream region C3 (see FIG. 6), and into an outer circumferential region A1, a first inner region A21 and a second inner region A22 (see FIG. 7).In the second and subsequent embodiments, in addition to the case where the first electrode 21 is divided into the outer circumferential region A1 and the inner region A2 (see FIG. 2), even when the first electrode 21 is divided in any other way than the above, the flow path forming conductors and the like can be formed based on the concept shown in the first embodiment.

[0083] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention.

[0084] The features of the present invention are as follows. [1] An electrolytic cell (2) including an electrolyte layer (20), a first electrode (21) provided on a first surface of the electrolyte layer, and a second electrode (22) provided on a second surface of the electrolyte layer opposite to the first surface; a first flow path (3) facing the first electrode; a second flow path (4) facing the second electrode; a flow path forming conductor (5) that contacts the first electrode and forms the first flow path, An electrolysis device (1) configured to generate hydrogen by electrolyzing a reaction fluid (F) that flows through the first flow path and is supplied to the first electrode by applying a voltage between the first electrode and the second electrode via the flow path forming conductor, When viewed from a normal direction (Z) of the first surface, the first electrode is divided into an outer circumferential region (A1) including an outer circumferential edge of the first electrode and an inner region (A2) inside the outer circumferential region, the outer shape of the inner region is similar to the outer shape of the first electrode, and the area of ​​the inner region is half the area of ​​the first electrode; When the amount of heat absorbed per unit area accompanying the electrolysis reaction in the electrolytic cell is defined as the endothermic density, an average value of endothermic heat density in the inner region being greater than an average value of endothermic heat density in the outer circumferential region. [2] The electrolysis device according to [1], wherein when the first electrode is divided into three equal parts in a width direction (Y) perpendicular to the flow path direction of the first flow path as viewed from the normal direction of the first surface, into a central region (B2) and two side regions (B1, B3) sandwiching the central region in the width direction, the average value of the endothermic heat density in the central region is greater than the average value of the endothermic heat density in the side regions. [3] The electrolysis device according to [1] or [2], wherein when the first electrode is divided into three equal parts in a flow path direction of the first flow path as viewed from a normal direction of the first surface, into an upstream region (C1), a midstream region (C2), and a downstream region (C3), the average value of the endothermic heat density in the midstream region is larger than the average value of the endothermic heat density in the upstream region and the average value of the endothermic heat density in the downstream region. [4] The electrolysis device according to [3], wherein the average value of the endothermic density in the downstream region is greater than the average value of the endothermic density in the upstream region. [5] The electrolysis device according to any one of [1] to [4], wherein when the inner region is divided into a first inner region (A21) and a second inner region (A22) surrounding the first inner region, which have similar outer shapes and equal areas, the average value of the endothermic density in the first inner region is greater than the average value of the endothermic density in the second inner region. [6] The electrolysis device according to any one of [1] to [5], wherein the flow path-forming conductor has a partition plate (51) that separates the first flow path and the first electrode, and a plurality of opening holes (31) are formed in the partition plate, and when viewed from the normal direction of the first surface, the opening ratios of the plurality of opening holes are made different among a plurality of regions, thereby providing a difference in the average values ​​of endothermic densities in the plurality of regions. [7] The electrolytic device according to [6], wherein the number density of the plurality of openings is made different among the plurality of regions. [8] The electrolysis device according to any one of [1] to [4], wherein the flow path-forming conductor has a plurality of protrusions (53) that abut against the first electrode, and when viewed from the normal direction of the first surface, the occupancy rates of the plurality of protrusions are made different among a plurality of regions, thereby making a difference in the average value of the endothermic heat density in the plurality of regions. [9] The electrolysis device according to any one of [1] to [4] and [8], wherein the height of the first flow path is made different among the plurality of regions, thereby making a difference in the average value of the endothermic density among the plurality of regions.

[10] The electrolysis device according to any one of [1] to [9], wherein the first electrode is made of a porous electrode material, and the porosity of the first electrode is made different among a plurality of regions, thereby making a difference in the average value of the endothermic density among the plurality of regions. [Explanation of symbols]

[0085] REFERENCE SIGNS LIST 1... electrolysis device, 2... electrolysis cell, 20... electrolyte layer, 21... first electrode, 22... second electrode, 3... first flow path, 4... second flow path, 5... flow path forming conductor, A1... outer peripheral region, A2... inner region

Claims

1. an electrolytic cell (2) including an electrolyte layer (20), a first electrode (21) provided on a first surface of the electrolyte layer, and a second electrode (22) provided on a second surface of the electrolyte layer opposite to the first surface; a first flow path (3) facing the first electrode; a second flow path (4) facing the second electrode; a flow path forming conductor (5) that contacts the first electrode and forms the first flow path, an electrolysis device (1) configured to generate hydrogen by electrolyzing a reaction fluid (F) that flows through the first flow path and is supplied to the first electrode by applying a voltage between the first electrode and the second electrode via the flow path forming conductor, When viewed from a normal direction (Z) of the first surface, the first electrode is divided into an outer circumferential region (A1) including an outer circumferential edge of the first electrode and an inner region (A2) inside the outer circumferential region, the outer shape of the inner region is similar to the outer shape of the first electrode, and the area of ​​the inner region is half the area of ​​the first electrode; When the amount of heat absorbed per unit area accompanying the electrolysis reaction in the electrolytic cell is defined as the endothermic density, an average value of endothermic heat density in the inner region being greater than an average value of endothermic heat density in the outer circumferential region.

2. 2. The electrolysis device according to claim 1, wherein when the first electrode is divided into three equal parts in a width direction (Y) orthogonal to a flow path direction of the first flow path as viewed from a normal direction of the first surface, into a central region (B2) and two side regions (B1, B3) sandwiching the central region in the width direction, an average value of the endothermic heat density in the central region is greater than an average value of the endothermic heat density in the side regions.

3. 3. The electrolysis device according to claim 1, wherein when the first electrode is divided into three equal parts in a flow path direction of the first flow path as viewed from a normal direction of the first surface, into an upstream region (C1), a midstream region (C2), and a downstream region (C3), an average value of the endothermic heat density in the midstream region is larger than an average value of the endothermic heat density in the upstream region and an average value of the endothermic heat density in the downstream region.

4. The electrolysis device according to claim 3 , wherein an average value of the endothermic heat density in the downstream region is greater than an average value of the endothermic heat density in the upstream region.

5. 3. The electrolysis device according to claim 1, wherein when the inner region is divided into a first inner region (A21) and a second inner region (A22) surrounding the first inner region, the first inner region and the second inner region having similar outer shapes and equal areas, the average value of the endothermic heat density in the first inner region is greater than the average value of the endothermic heat density in the second inner region.

6. 3. The electrolysis device according to claim 1, wherein the flow path-forming conductor has a partition plate (51) that separates the first flow path and the first electrode, and a plurality of opening holes (31) are formed in the partition plate, and when viewed from the normal direction of the first surface, opening rates of the plurality of opening holes are made different among a plurality of regions, thereby providing differences in average values ​​of endothermic densities in the plurality of regions.

7. 7. The electrolytic device according to claim 6, wherein the number density of the open holes is varied among the plurality of regions.

8. 3. The electrolysis device according to claim 1, wherein the flow path-forming conductor has a plurality of protrusions (53) that abut against the first electrode, and when viewed from a normal direction of the first surface, an occupancy rate of the plurality of protrusions is made different among a plurality of regions, thereby providing a difference in an average value of endothermic density in the plurality of regions.

9. The electrolysis device according to claim 1 or 2, wherein heights of the first flow paths are made different among the plurality of regions, thereby providing differences in average values ​​of endothermic densities among the plurality of regions.

10. 3. The electrolysis device according to claim 1, wherein the first electrode is made of a porous electrode material, and a porosity of the first electrode is made different among a plurality of regions, thereby providing a difference in average values ​​of endothermic densities among the plurality of regions.

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