Electrochemistry Module

Abstract

To provide an electrochemical module in which size increase in the stacking direction is suppressed while increasing an output of an electrochemical reaction.SOLUTION: An electrochemical module 12 is formed by stacking a plurality of membrane electrode assemblies 34 having electrolyte membranes 34a, anodes 34b and cathodes 34c. The plurality of membrane electrode assemblies 34 are stacked so that a first region 46 where the anodes 34b face each other and a second region 48 where the cathodes 34c face each other appear alternately in the stacking direction. Further, at least one of the first region 46 and the second region 48 includes common flow paths 50 and 52 shared by two adjacent membrane electrode assemblies 34.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrochemical module in which a plurality of electrolyte membranes are stacked. [Background technology]

[0002] In recent years, research and development has been conducted on electrochemical modules that contribute to more efficient energy use in order to provide affordable, reliable, sustainable and advanced energy to more people.

[0003] Examples of such electrochemical modules include differential pressure water electrolysis devices and electrochemical hydrogen pumps. These electrochemical modules have a structure in which a plurality of unit cells, each including an electrolyte membrane, are stacked (see, for example, Patent Document 1). Each unit cell has a membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, a flow path for supplying a fluid such as gas or water to each of the anode electrode and the cathode electrode, and a pair of separator plates that form the flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-89229 Summary of the Invention [Problem to be solved by the invention]

[0005] In an electrochemical module, to increase the throughput of electrochemical reactions, it is necessary to increase the number of stacked unit cells. However, increasing the number of stacked unit cells results in an increase in the size of the electrochemical module in the stacking direction of the unit cells.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] One aspect of the following disclosure is an electrochemical module in which a plurality of membrane electrode assemblies are stacked, each having an electrolyte membrane and an anode electrode and a cathode electrode sandwiching the electrolyte membrane, the plurality of membrane electrode assemblies being stacked such that first regions in which the anode electrodes face each other and second regions in which the cathode electrodes face each other alternate in the stacking direction, and at least one of the first regions and the second regions is provided with a common flow path shared by two adjacent membrane electrode assemblies. [Effects of the Invention]

[0008] The electrochemical module described above can increase the throughput of the electrochemical reaction while suppressing an increase in size in the stacking direction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a hydrogen pump according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the hydrogen pump of FIG. [Figure 3] FIG. 3 is a cross-sectional view of the electrochemical module of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The hydrogen pump 10 according to the embodiment shown in Figure 1 is an electrochemical hydrogen pump that boosts hydrogen pressure through an electrochemical reaction. The hydrogen pump 10 is used in energy storage systems that compress and store hydrogen produced using surplus electricity, hydrogen stations that supply hydrogen to mobile vehicles, and the like.

[0011] As shown in Figure 2, the hydrogen pump 10 includes an electrochemical module 12, a pair of insulating plates 14, a cylinder unit 16, a pair of end plates 18, and a stud bolt 20. The electrochemical module 12 has a structure in which a plurality of unit structures 22 are stacked. In this specification, the direction in which the unit structures 22 of the electrochemical module 12 are stacked (the thickness direction of the membrane electrode assembly 34) is referred to as the stacking direction. Furthermore, one direction in the stacking direction (downward in Figure 1) is referred to as the first direction, and the direction opposite to the first direction is referred to as the second direction.

[0012] The electrochemical module 12 is sandwiched between a pair of insulating plates 14 and insulated from the end plates 18. The cylinder unit 16 is disposed between one of the end plates 18 and the insulating plate 14. The cylinder unit 16 incorporates an elastic member and applies a predetermined compressive force to the electrochemical module 12.

[0013] The pair of end plates 18 sandwich the electrochemical module 12 and the cylinder unit 16 in the first and second stacking directions, and apply a predetermined fastening load to the electrochemical module 12. The fastening load of the end plates 18 is generated by attaching a plurality of stud bolts 20 to the pair of end plates 18 and tightening them with nuts 24.

[0014] The electrochemical module 12 has a cylindrical shape. The electrochemical module 12 has a first communication hole 26 extending in the stacking direction in the center. The first communication hole 26 serves as a flow path for hydrogen output from the electrolyte membrane 34a as a result of the electrochemical reaction (see FIG. 3). The first communication hole 26 communicates with first communication holes 28 provided in the centers of the insulating plate 14, the cylinder unit 16, and the end plate 18.

[0015] The electrochemical module 12 has a pair of refrigerant supply / discharge units 30 that supply refrigerant to its sides, and a pair of hydrogen supply / discharge units 32 that supply low-pressure hydrogen gas. As shown in FIG. 2 , the pair of refrigerant supply / discharge units 30 are arranged 180° apart in the circumferential direction. One refrigerant supply / discharge unit 30 has a second communication hole 30a through which the refrigerant is supplied, and the other refrigerant supply / discharge unit 30 has a third communication hole 30b through which the refrigerant is discharged. The pair of hydrogen supply / discharge units 32 are arranged 180° apart in the circumferential direction. The hydrogen supply / discharge unit 32 is arranged 90° apart in the circumferential direction from the refrigerant supply / discharge unit 30. One hydrogen supply / discharge unit 32 has a fourth communication hole 32a through which hydrogen is supplied, and the other hydrogen supply / discharge unit 32 has a fifth communication hole 32b through which hydrogen is discharged. The direction connecting the pair of hydrogen supply / discharge units 32 is referred to as the third direction, and the direction connecting the pair of refrigerant supply / discharge units 30 is referred to as the fourth direction. The third direction and the fourth direction are perpendicular to each other.

[0016] The electrochemical module 12 is formed by stacking a plurality of unit structures 22. In this specification, the term "unit structure 22" is used to refer to the smallest structural unit repeated in the stacking direction. In this embodiment, as will be described later, one unit structure 22 includes two layers of electrolyte membrane 34a. The number of stacked unit structures 22 that constitute the electrochemical module 12 is not limited to the example shown in the figure. An electrochemical module 12 that achieves a practical throughput may include several to several hundred layers of unit structures 22. The electrochemical module 12 and the unit structures 22 will be described in detail below.

[0017] 3 includes two stacked unit structures 22. Each unit structure 22 has, as its main components, a first membrane electrode assembly 341, a second membrane electrode assembly 342, a first support plate 361, a second support plate 362, a conductive plate 38, a spacer 40, a packing 42, and a pressure-resistant body 44. The first membrane electrode assembly 341 and the second membrane electrode assembly 342 are collectively referred to as the membrane electrode assembly 34.

[0018] The membrane electrode assembly 34 includes an electrolyte membrane 34a, an anode electrode 34b, a cathode electrode 34c, and a resin frame 34d. The electrolyte membrane 34a, the anode electrode 34b, and the cathode electrode 34c are located in a reaction region 35A where an electrochemical reaction takes place, and the resin frame 34d is located in a peripheral region 35B surrounding the reaction region 35A. The anode electrode 34b converts supplied hydrogen gas into H + Ions (protons) are generated. The electrolyte membrane 34a transfers the protons from the anode electrode 34b to the cathode electrode 34c. The cathode electrode 34c generates hydrogen gas from the protons. When a voltage is applied between the anode electrode 34b and the cathode electrode 34c, the membrane electrode assembly 34 transfers hydrogen gas from the anode electrode 34b to the cathode electrode 34c.

[0019] The resin frame 34d is a circular ring-shaped resin member that is joined to and supports the electrolyte membrane 34a. The resin frame 34d is located in the peripheral region 35B of the membrane electrode assembly 34 and surrounds the periphery of the electrolyte membrane 34a (reaction region 35A). The resin frame 34d abuts against the packing 42 and the pressure-resistant body 44, sealing gaps in the membrane electrode assembly 34 and preventing leakage of hydrogen gas.

[0020] The first membrane electrode assembly 341 is a membrane electrode assembly 34 in which the anode electrode 34b faces in a first direction and the cathode electrode 34c faces in a second direction. The second membrane electrode assembly 342 is a membrane electrode assembly 34 in which the anode electrode 34b faces in the second direction and the cathode electrode 34c faces in the first direction. In the electrochemical module 12, the first membrane electrode assembly 341 and the second membrane electrode assembly 342 are alternately arranged in the stacking direction.

[0021] A first region 46, in which the cathode electrodes 34c face each other, is formed between the first membrane electrode assembly 341 and the second membrane electrode assembly 342 adjacent thereto in the second direction. A second region 48 is formed at the joint between two unit structures 22. That is, the second region 48 is formed between the first membrane electrode assembly 341 belonging to one unit structure 22 and the second membrane electrode assembly 342 belonging to the other unit structure 22. The first regions 46 and the second regions 48 appear alternately in the stacking direction.

[0022] A pair of conductive plates 38 and a spacer 40 are arranged in the first region 46. The pair of conductive plates 38 sandwich the spacer 40 in the stacking direction. One conductive plate 38 abuts against the cathode electrode 34c of the first membrane electrode assembly 341, and the other conductive plate 38 abuts against the cathode electrode 34c of the second membrane electrode assembly 342. The conductive plate 38 is made of a porous conductive material. The conductive plate 38 is made of a porous conductive material. The conductive plate 38 is made of a porous conductive material. The conductive plate 38 abuts against the cathode electrode 34c of the first membrane electrode assembly 341. and second membrane electrode assembly 342 The conductive plate 38 allows hydrogen generated at the cathode electrode 34c to pass through. The conductive plate 38 also forms a part of a power supply path that supplies current to the cathode electrode 34c.

[0023] The spacer 40 is positioned between the pair of conductive plates 38. The spacer 40 is formed from a metal plate having electrical conductivity and moderate elasticity, such as stainless steel. The spacer 40 electrically connects the pair of cathode electrodes 34c facing each other in the first region 46 via the conductive plates 38. The spacer 40 has a flat portion 40a and a plurality of leaf spring portions 40b protruding from the flat portion 40a in the stacking direction. The flat portion 40a abuts against one conductive plate 38, and the leaf spring portions 40b abut against the other conductive plate 38, thereby separating the pair of conductive plates 38.

[0024] The spacer 40 forms a cathode common flow path 50 through which hydrogen gas can flow between the pair of conductive plates 38. The cathode common flow path 50 is a flow path shared by the first membrane electrode assembly 341 and the second membrane electrode assembly 342 that are adjacent in the stacking direction. The cathode common flow path 50 collects hydrogen gas generated at the pair of cathode electrodes 34c and distributes it toward the first communication holes 26, 28 (FIG. 2).

[0025] A packing 42 and a pressure-resistant barrel 44 are disposed in the peripheral region 35B of the first region 46. The packing 42 is located inside the pressure-resistant barrel 44 and is formed in a circular ring shape surrounding the reaction region 35A. The packing 42 is made of an elastic material such as rubber. The packing 42 adheres closely to the resin frame 34d of the first membrane electrode assembly 341 and the resin frame 34d of the second membrane electrode assembly 342, sealing the cathode common flow path 50.

[0026] The pressure-resistant barrel 44 is formed in a circular ring shape. The inner diameter of the pressure-resistant barrel 44 is larger than the outer diameter of the packing 42. The pressure-resistant barrel 44 has enough strength to not deform due to the internal pressure of the cathode common flow path 50. The pressure-resistant barrel 44 surrounds the periphery of the packing 42, preventing the packing 42 from expanding and maintaining the airtightness of the packing 42.

[0027] In the second region 48, a first support plate 361 belonging to one unit structure 22 and a second support plate 362 belonging to the other unit structure 22 are arranged. In the second region 48, the first support plate 361 and the second support plate 362 are joined by a method such as diffusion bonding to form an integrated support plate 36. The support plate 36 bears the deformation stress of the membrane electrode assembly 34 due to the pressure difference between the first region 46 and the second region 48. The support plate 36 also forms an anode common flow path 52 in the second region 48 through which hydrogen gas can flow.

[0028] The first support plate 361 and the second support plate 362 are members of the same shape. The first support plate 361 is disposed with its outer surface 36a facing the membrane electrode assembly 34 on the second direction side. The second support plate 362 is disposed with its outer surface 36a facing the membrane electrode assembly 34 on the first direction side. In other words, the first support plate 361 and the second support plate 362 are disposed facing opposite directions in the stacking direction. Inside the stacked unit structures 22, the first support plate 361 and the second support plate 362 are joined to each other to form an integrated support plate 36.

[0029] The first support plate 361 and the second support plate 362 have open grooves 52a on their outer surfaces 36a. The open grooves 52a are arranged in portions facing the reaction regions 35A of the membrane electrode assembly 34. The open grooves 52a extend in the third direction. The open grooves 52a open toward the membrane electrode assembly 34. The open grooves 52a form part of the anode common flow path 52 and supply low-pressure hydrogen gas to the first membrane electrode assembly 341 and the second membrane electrode assembly 342.

[0030] The first support plate 361 also has a closed groove 52b and a refrigerant groove 54a on its inner surface 36b facing the second support plate 362. The closed groove 52b is located outside the reaction region 35A of the membrane electrode assembly 34. In other words, the closed groove 52b is located in the peripheral region 35B. When the first support plate 361 and the second support plate 362 are joined together, the closed groove 52b forms a flow path that is closed in the stacking direction. The closed groove 52b communicates with the open groove 52a on the outer surface 36a via a through hole 52c. The anode common flow path 52 is composed of the closed groove 52b, the through hole 52c, and the open groove 52a. One end of the anode common flow path 52 in the third direction communicates with the fourth communication hole 32a, and the other end in the third direction communicates with the fifth communication hole 32b. The anode common flow path 52 is shared by two membrane electrode assemblies 34 adjacent to the support plate 36 and allows hydrogen gas to flow therethrough.

[0031] The coolant grooves 54a extend in a fourth direction, which is a direction perpendicular to the plane of the paper in Figure 3. When the first support plate 361 and the second support plate 362 are joined, the coolant grooves 54a are closed in the stacking direction to form coolant channels 54 extending in the fourth direction. Water, for example, flows through the coolant channels 54 as a coolant. The coolant channels 54 cool the membrane electrode assembly 34, which generates heat due to an electrochemical reaction.

[0032] The pair of anode electrodes 34b sandwiching the second region 48 are electrically insulated from each other. To prevent electrical conduction between these anode electrodes 34b, it is preferable that at least a portion of the support plate 36 be made of an insulator.

[0033] An end separator 56 is attached to each of the first support plate 361 located at the end in the first direction and the second support plate 362 located at the end in the second direction. The end separator 56 covers the inner surface 36b of the first support plate 361 and the inner surface 36b of the second support plate 362. The end separator 56 closes the closing grooves 52b and the refrigerant grooves 54a in the stacking direction, preventing leakage of hydrogen gas and the refrigerant.

[0034] In the electrochemical module 12, the cathode electrodes 34c of a pair of membrane electrode assemblies 34 that sandwich the first region 46 are electrically connected to each other. Furthermore, the anode electrodes 34b of the membrane electrode assemblies 34 that sandwich the first region 46 are electrically connected to each other. That is, the anode electrodes 34b belonging to one unit structure 22 are electrically connected to each other, and the cathode electrodes 34c are electrically connected to each other via the spacers 40. In this case, as shown in the figure, the power supply device 58 may supply a driving current in parallel to each of the anode electrodes 34b and cathode electrodes 34c of each unit structure 22.

[0035] Furthermore, in the electrochemical module 12, a plurality of unit structures 22 may be connected in series. In this case, for example, the anode electrode 34b of a unit structure 22 located on the first direction side is electrically connected to the cathode electrode 34c of an adjacent unit structure 22 on the second direction side. By making such a connection for all unit structures 22, a series connection of a plurality of unit structures 22 is realized.

[0036] The electrochemical module 12 of this embodiment is configured as described above. The electrochemical module 12 operates as follows.

[0037] Low-pressure hydrogen gas is supplied to the anode common flow channel 52 of the support plate of the electrochemical module 12 through the hydrogen supply / discharge unit 32. The hydrogen gas is supplied to the anode electrode b of the membrane electrode assembly .

[0038] The membrane electrode assemblies 34 electrochemically move the hydrogen gas to the cathode common flow path 50 on the higher pressure side. The movement of the hydrogen gas by the membrane electrode assemblies 34 occurs against a pressure difference. As a result, the pressure of the hydrogen gas is increased. The hydrogen gas produced by the two membrane electrode assemblies 34 is guided to the first communication holes 26, 28 through the cathode common flow path 50. In this way, the electrochemical module 12 increases the pressure of the hydrogen gas.

[0039] The electrochemical module 12 of the present embodiment described above has a cathode common flow path 50 shared by the first membrane electrode assembly 341 and the second membrane electrode assembly 342 in the first region 46 where the pair of cathode electrodes 34c face each other. Therefore, the electrochemical module 12 can reduce the number of separators compared to conventional devices in which a pair of separators is provided for each membrane electrode assembly 34, and the dimension of the electrochemical module 12 in the stacking direction can be reduced.

[0040] (Modification 1 of the first embodiment) Although the above description has been given of an example of the electrochemical module 12 of the hydrogen pump 10, this embodiment is not limited to this. The electrochemical module 12 can be used in a water electrolysis device. In this case, the electrochemical module 12 electrolyzes water supplied from the anode common flow path 52 to generate hydrogen gas in the cathode common flow path 50 and oxygen gas in the anode common flow path 52.

[0041] (Modification 2 of the first embodiment) The electrochemical module 12 is configured to apply OH to the electrolyte membrane 34a. -A water electrolysis device can be configured using an anion conductive membrane that allows ions to move. In this case, the anode electrode 34b and the cathode electrode 34c of the membrane electrode assembly 34 are arranged in the opposite direction to that shown in FIG. 3. The support plate 36 is arranged in the first region 46, and the conductive plate 38 and the spacer 40 are arranged in the second region 48. The anode common flow path 52 in the second region 48 communicates with the first communication holes 26, 28. The cathode common flow path 50 in the first region 46 communicates with the fourth communication hole 32a and the fifth communication hole 32b. In this case, water is supplied to the electrochemical module 12 from the cathode common flow path 50. The electrochemical module 12 outputs hydrogen from the cathode common flow path 50 and high-pressure oxygen gas from the anode common flow path 52.

[0042] In addition to the above disclosure, the following additional information is disclosed.

[0043] (Supplementary Note 1) One aspect of the disclosure is an electrochemical module 12 in which a plurality of membrane electrode assemblies 34 are stacked, each having an electrolyte membrane 34a and an anode electrode 34b and a cathode electrode 34c sandwiching the electrolyte membrane, the plurality of membrane electrode assemblies being stacked so that first regions 46 in which the anode electrodes face each other and second regions 48 in which the cathode electrodes face each other alternate in the stacking direction, and at least one of the first regions and the second regions is provided with common flow channels 50, 52 shared by two adjacent membrane electrode assemblies. This electrochemical module does not require the placement of a separator in the common flow channel, allowing for a reduced dimension in the stacking direction.

[0044] (Supplementary Note 2) In the electrochemical module according to Supplementary Note 1, the common flow path may be provided in each of the first region and the second region. By increasing the number of common flow paths, the size of this electrochemical module in the stacking direction can be further reduced.

[0045] (Supplementary Note 3) In the electrochemical module according to Supplementary Note 2, the common flow path of either the first region or the second region may pass a high-pressure fluid pressurized by two adjacent membrane electrode assemblies. This electrochemical module does not require a thick separator that can withstand high pressure, thereby reducing the thickness in the stacking direction.

[0046] (Supplementary Note 4) The electrochemical module according to Supplementary Note 3 may include a spacer 40 that is disposed in the common flow path through which the high-pressure fluid flows and separates two adjacent membrane electrode assemblies. This electrochemical module can prevent clogging of the common flow path formed in the first region.

[0047] (Supplementary Note 5) In the electrochemical module according to Supplementary Note 4, the spacer may electrically connect the electrodes of the adjacent membrane electrode assemblies, which allows for a simplified wiring structure of the electrochemical module.

[0048] (Supplementary Note 6) The electrochemical module according to any one of Supplementary Notes 3 to 5 may include a support plate 36 disposed in the common flow path through which a low-pressure fluid flows, for supplying the fluid to two adjacent membrane electrode assemblies. This electrochemical module can prevent the common flow path on the low-pressure side from being blocked by a pressure difference.

[0049] (Supplementary Note 7) In the electrochemical module described in Supplementary Note 6, the support plate may have a coolant flow path 54 therein through which a coolant flows, and the coolant flow path may cool two adjacent membrane electrode assemblies. In this electrochemical module, two membrane electrode assemblies can be cooled by one support plate, so the thickness in the stacking direction can be further reduced.

[0050] (Appendix 8) In the electrochemical module according to appendix 6 or 7, the support plate may prevent electrical conduction between the electrodes of adjacent membrane electrode assemblies. This electrochemical module allows a plurality of unit structures to be connected in series by electrically insulating the unit structures from each other.

[0051] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0052] 10...Hydrogen pump 12...Electrochemical module 22... Unit structure 26, 28... First communication hole 34...Membrane electrode structure 34a...Electrolyte membrane 34b...anode electrode 34c...cathode electrode 36...Support plate 40...Spacer 46...First area 48...Second area 54... refrigerant flow path 341... first membrane electrode assembly 342...Second membrane electrode structure

Claims

1. An electrochemical module in which a plurality of membrane electrode assemblies each having an electrolyte membrane and an anode electrode and a cathode electrode sandwiching the electrolyte membrane are stacked, the plurality of membrane electrode assemblies are stacked such that first regions in which the anode electrodes face each other and second regions in which the cathode electrodes face each other alternate in the stacking direction; each of the first region and the second region includes a common flow path shared by two adjacent membrane electrode assemblies; a support plate having a coolant flow path therein through which a coolant flows is disposed in the common flow path of either the first region or the second region; The coolant flow passages cool two adjacent membrane electrode assemblies.

2. 2. The electrochemical module according to claim 1, wherein the common flow path of the other of the first region and the second region passes a high-pressure fluid pressurized by two adjacent membrane electrode assemblies.

3. 3. The electrochemical module according to claim 2, further comprising a spacer disposed in the common flow path through which the high-pressure fluid flows, the spacer separating two adjacent membrane electrode assemblies.

4. 4. The electrochemical module according to claim 3, wherein the spacer electrically connects the electrodes of the adjacent membrane electrode assemblies.

5. 5. The electrochemical module according to claim 1, wherein a low-pressure fluid flows through the common flow channel in which the support plate is disposed.

6. 6. The electrochemical module according to claim 5, wherein the support plate prevents electrical conduction between the electrodes of adjacent membrane electrode assemblies.

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