JP2017123249A - Separator for solid polymer type fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a solid polymer type fuel battery that can enhance power generation performance.SOLUTION: A separator 30 for a solid polymer type fuel battery is disposed to face a gas diffusion layer of a membrane electrode assembly. The separator 30 includes a groove group 34 having an oxidant gas supply hole 13, an oxidant gas discharge hole 15, and plural gas flow path grooves which are formed in a counter surface 31 opposed to the gas diffusion layer and extend from the oxidant gas supply hole 13 side to the oxidant gas discharge hole 15 side. The groove group 34 includes a single gas inflow path groove 35 which has an upstream end 351 intercommunicating with the oxidant gas supply hole 13 and a closed downstream end 352, and a single gas outflow path groove 36 having a closed upstream end 361, and a downstream end 362 intercommunicating with the oxidant gas discharge hole 15. The gas flow grooves intersect to a virtual straight line V perpendicular to the extension direction L of the gas flow path grooves at three or more places.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a separator disposed to face a gas diffusion layer of a membrane electrode assembly of a polymer electrolyte fuel cell.

  A stack of polymer electrolyte fuel cells is formed by stacking a large number of power generation cells. The power generation cell includes a sheet-like membrane electrode assembly and a pair of separators disposed on both sides of the membrane electrode assembly.

  The membrane electrode assembly includes a solid electrolyte membrane and a cathode side electrode layer and an anode side electrode layer disposed on both sides of the solid electrolyte membrane, respectively. Each of the cathode electrode layer and the anode electrode layer has a catalyst layer and a gas diffusion layer, and the gas diffusion layers on the cathode side and the anode side face the pair of separators, respectively.

  The separator is formed with gas supply holes and gas discharge holes (also referred to as gas manifolds) for supplying and discharging fuel gas and oxidizing gas (hereinafter referred to as reaction gas). Further, a plurality of gas flow channel grooves extending from the gas supply hole side toward the gas discharge hole side are formed on the facing surface of the separator that faces the gas diffusion layer (see, for example, Patent Document 1).

  In the separator described in Patent Document 1, as shown in FIG. 1 of the same document, a supply gas flow channel groove whose upstream end is in communication with the gas supply hole and whose downstream end is closed, and the upstream end is closed. At the same time, exhaust gas passage grooves whose downstream ends communicate with the gas exhaust holes are alternately formed. The supply gas flow channel groove and the discharge gas flow channel groove both extend linearly as a whole. In the power generation cell including such a separator, the reaction gas supplied from the gas supply hole flows through the supply gas flow channel groove and flows into the gas diffusion layer to be diffused for power generation. Further, the remaining reaction gas that has not been used for power generation flows out from the gas diffusion layer into the discharge gas passage groove as an off-gas, and is discharged into the gas discharge hole. According to such a separator, the diffusibility of the reaction gas is improved.

JP 2005-100813 A

  By the way, in the separator described in Patent Document 1, the number of supply gas passage grooves is an abbreviation of the number of gas passage grooves (the sum of the number of supply gas passage grooves and the number of discharge gas passage grooves). It is half. Therefore, the increase in the number of inlet portions communicating with the gas supply holes tends to slow the flow rate of the reaction gas in each gas flow channel groove, and water generated by power generation (hereinafter, generated water) is gas flow channels. It tends to stay in the groove. As a result, the pressure loss of the reaction gas increases, leaving room for improvement in improving power generation performance.

  An object of the present invention is to provide a polymer electrolyte fuel cell separator capable of improving power generation performance.

  A separator for a polymer electrolyte fuel cell for achieving the above object is a separator disposed to face a gas diffusion layer of a membrane electrode assembly of a polymer electrolyte fuel cell, comprising a gas supply hole, a gas A discharge hole and a groove group formed on a facing surface facing the gas diffusion layer and including a plurality of gas flow channel grooves extending from the gas supply hole side toward the gas discharge hole side; The groove group includes, as the gas flow channel groove, a single gas inflow channel groove whose upstream end communicates with the gas supply hole and whose downstream end is blocked; The gas flow path groove communicates with the gas discharge hole, and the gas flow path groove intersects with a virtual straight line intersecting with the extending direction of the gas flow path groove at three or more locations.

  According to this configuration, since the groove group has a single gas inflow passage groove, the number of inlet portions communicating with the gas supply hole is one. As a result, the number of gas flow channel groove inlet portions is reduced compared to the conventional configuration, so that the flow rate of the reaction gas in the gas inflow channel groove can be increased, and the flow rate of the reaction gas in the gas diffusion layer is increased. be able to.

  Further, according to the above configuration, since the gas flow channel grooves intersect at three or more locations with respect to the virtual straight line that intersects the extending direction of the gas flow channel groove, the length of the gas flow channel groove in the extending direction The channel length of the entire gas channel groove can be ensured while shortening. As a result, it is possible to appropriately retain the generated water in the gas flow channel groove while increasing the flow rate of the reaction gas, and the humidity can be appropriately maintained.

  According to the present invention, power generation performance can be improved.

The disassembled perspective view which decomposes | disassembles and shows the fuel cell to which the separator was applied about one Embodiment of the separator for polymer electrolyte fuel cells. The perspective view which shows the separator by the side of a cathode. The perspective view which shows the opposing surface of the separator by the side of a cathode. The perspective view which shows the separator by the side of an anode. The perspective view which shows a flame | frame. (A) is sectional drawing which shows the cross-section of the electric power generation cell along the 6a-6a line of FIG. 2, (b) is sectional drawing which shows the cross-section of a membrane electrode assembly. The top view which shows the opposing surface of the separator by the side of a cathode. The top view which shows the opposing surface of the separator by the side of the cathode in a modification. The top view which shows the opposing surface of the separator by the side of the cathode in another modification. The top view which shows the opposing surface of the separator by the side of the cathode in another modification.

Hereinafter, an embodiment will be described with reference to FIGS.
As shown in FIGS. 1 and 6A, a stack of polymer electrolyte fuel cells (hereinafter referred to as fuel cells) is formed by stacking a large number of power generation cells 11.

  The power generation cell 11 has a rectangular shape and includes a sheet-like membrane electrode assembly 12 and a pair of separators 30 and 40 disposed on both sides of the membrane electrode assembly 12. The pair of separators 30 and 40 is formed, for example, by press-molding a thin metal plate such as titanium or stainless steel.

  As shown to Fig.6 (a), the separators 30 and 40 of the adjacent electric power generation cell 11 are contact | abutted. A seal frame 50 made of an electrically insulating material is interposed between the outer peripheral portions of the adjacent power generation cells 11. The space between the outer peripheral portions of the power generation cell 11 is sealed by the seal frame 50 and the interval between the outer peripheral portions is maintained. Note that the relative relationships among the thicknesses of the membrane electrode assembly 12, the separators 30 and 40, and the seal frame 50 are different from actual ones.

  As shown in FIGS. 1 to 6A, the membrane electrode assembly 12, the separators 30 and 40, and the seal frame 50 of the power generation cell 11 are provided with an oxidizing gas supply hole 13, a fuel gas supply hole 14, and an oxidizing gas discharge hole. 15 and a fuel gas discharge hole 16 are provided therethrough. The oxidizing gas supply hole 13 and the oxidizing gas discharge hole 15 are formed at diagonal positions. The fuel gas supply hole 14 and the fuel gas discharge hole 16 are formed at diagonal positions. In the present embodiment, an oxidizing gas supply hole 13 and a fuel gas supply hole 14 are formed on one end side in the longitudinal direction of the power generation cell 11, and an oxidizing gas discharge hole 15 and a fuel gas discharge hole are formed on the other end side in the longitudinal direction. 16 is formed.

<Membrane electrode assembly 12>
As shown in FIG. 6B, the membrane electrode assembly 12 includes a solid electrolyte membrane 21, and a cathode side electrode layer 22 and an anode side electrode layer 23 disposed on both sides of the solid electrolyte membrane 21. Both the cathode-side electrode layer 22 and the anode-side electrode layer 23 have a catalyst layer 24 and a gas diffusion layer 25, and the cathode-side and anode-side gas diffusion layers 25 are arranged to face the pair of separators 30 and 40, respectively. Is done.

<Separator 30 on the cathode side>
As shown in FIGS. 2, 3, and 7, on the facing surface 31 of the separator 30 that faces the gas diffusion layer 25, there are four connection grooves 32 connected to the oxidizing gas supply hole 13, and each of the connection grooves 32. A gas distribution groove 33 connected to the downstream end is formed. The gas distribution groove 33 extends along the short direction of the separator 30.

  Further, on the opposing surface 31, four connection grooves 38 connected to the oxidizing gas discharge hole 15 and a gas collecting groove 37 to which the upstream end of each connection groove 38 is connected are formed. The gas collecting groove 37 extends along the short direction of the separator 30.

  Between the gas distribution groove 33 and the gas collecting groove 37, a plurality of groove groups 34 each including a plurality of gas flow channel grooves extending from the oxidizing gas supply hole 13 side toward the oxidizing gas discharge hole 15 side are formed. ing. In the present embodiment, three groove groups 34 are juxtaposed in the short direction of the separator 30.

The groove group 34 has a single gas inflow channel groove 35 and a single gas outflow channel groove 36 as the gas flow channel grooves.
As shown in FIG. 7, the upstream end 351 of the gas inflow channel groove 35 is connected to the gas distribution groove 33 and communicates with the oxidizing gas supply hole 13 through the connection groove 32 and the gas distribution groove 33. The downstream end 352 of the gas inflow channel groove 35 is closed. Further, the gas inflow channel groove 35 is folded back toward the gas distribution groove 33 in the middle thereof.

  The downstream end 362 of the gas outflow channel groove 36 is connected to the gas collecting groove 37 and communicates with the oxidizing gas discharge hole 15 through the gas collecting groove 37 and the connecting groove 38. The upstream end 361 of the gas outflow channel groove 36 is closed. Further, the gas outflow channel groove 36 is folded back toward the gas collecting groove 37 in the middle thereof.

  The gas inflow channel groove 35 is folded back so as to sandwich the folded portion 363 of the gas outflow channel groove 36. Further, the gas outflow channel groove 36 is folded back so as to sandwich the folded portion 353 of the gas inflow channel groove 35. Therefore, in the groove group 34, the gas flow path grooves intersect at four locations with respect to the virtual straight line V orthogonal to the extending direction L of the gas flow path grooves (longitudinal direction of the separator 30).

<Anode separator 40>
As shown in FIGS. 1 and 4, the anode-side separator 40 has the same shape as the cathode-side separator 30. However, as illustrated in FIG. 4, the anode-side separator 40 is stacked in a posture (see FIG. 3) in which the cathode-side separator 30 is turned over. Therefore, for each part of the anode-side separator 40, a sign “4 *” is obtained by adding “10” to a sign “3 *” of each part (excluding the holes 13 to 18) of the cathode-side separator 30. The description is omitted by attaching.

<Seal frame 50>
As shown in FIGS. 1 and 5, the seal frame 50 is formed with three support protrusions 51 and 52, and these support protrusions 51 and 52 are connection grooves of the cathode-side separator 30. The ridges 39 are supported by being fitted between the ridges 39 formed on the back surfaces of 32 and 38, respectively. Also, the seal frame 50 is formed with three support protrusions 53 and 54, and these support protrusions 51 and 52 are formed on the back surfaces of the connection grooves 42 and 48 of the separator 40 on the anode side. The ridges are supported by being fitted between the ridges.

Next, the basic operation of the fuel cell will be described.
For example, fuel gas such as hydrogen is distributed and supplied from the fuel gas supply hole 14 into the gas inflow channel grooves 45 of the three groove groups 44 through the connection grooves 42 and the gas distribution grooves 43. The fuel gas flows into the gas diffusion layer 25 on the anode side of the membrane electrode assembly 12 and is diffused to be supplied to the catalyst layer 24 of the anode side electrode layer 23.

  The oxidizing gas is distributed and supplied from the oxidizing gas supply hole 13 into the gas inflow channel grooves 35 of the three groove groups 34 via the connection grooves 32 and the gas distribution grooves 33. The oxidizing gas flows into the gas diffusion layer 25 on the cathode side of the membrane electrode assembly 12 and is diffused to be supplied to the catalyst layer 24 of the cathode side electrode layer 22.

  In the catalyst layer 24 on the anode side, the fuel gas is decomposed into hydrogen ions and electrons. Then, the hydrogen ions pass through the solid electrolyte membrane 21 and the electrons pass through a conductor (not shown) and move to the cathode side electrode layer 22.

  Hydrogen ions that have moved to the cathode electrode layer 22 through the solid electrolyte membrane 21 and electrons that have moved through the conductor react with the oxidizing gas (oxygen) in the catalyst layer 24 on the cathode side. Water is produced. Electricity is generated by the electrochemical reaction at this time.

  The remaining fuel gas that has not been used for power generation flows into the gas outlet groove 46 of each groove group 44 from the gas diffusion layer 25 on the anode side as a fuel off gas, and is collected in the gas collecting groove 47 before being connected to the connecting groove 48. Through the fuel gas discharge hole 16.

  The remaining oxidizing gas that has not been used for power generation flows into the gas outlet groove 36 of each groove group 34 from the gas diffusion layer 25 on the cathode side as an oxidizing off gas, and is collected in the gas collecting groove 37 before being connected to the connecting groove 38. Is discharged into the oxidizing gas discharge hole 15.

  Although not shown, the cooling water supplied from the cooling water supply hole 17 is cooled between the separators 30 and 40 of the adjacent power generation cells 11 connected to the cooling water supply hole 17 and the cooling water discharge hole 18. A flow path for flowing toward the water discharge hole 18 is formed.

According to the solid polymer fuel cell separator according to the present embodiment described above, the following effects can be obtained.
(1) The groove group 34 is a gas channel groove, and the upstream end 351 communicates with the oxidizing gas supply hole 13 and the downstream end 352 is closed, and the upstream end 361 is closed. In addition, the downstream end 362 has a gas outflow channel groove 36 communicated with the oxidizing gas discharge hole 15. Three or more gas flow channel grooves intersect with a virtual straight line V orthogonal to the extending direction L of the gas flow channel groove.

  According to such a configuration, each groove group 34 has a single gas inflow passage groove 35, so that the number of inlet portions communicating with the oxidizing gas supply hole 13 is one for each groove group 34. As a result, the number of inlet portions of the gas flow channel groove is reduced as compared with the conventional configuration, so that the flow rate of the oxidizing gas in the gas inflow channel groove 35 can be increased, and the flow rate of the oxidizing gas in the gas diffusion layer 25 is reduced. Can be fast. Similarly, the flow rate of the fuel gas in the gas inflow channel groove 45 can be increased, and the flow rate of the fuel gas in the gas diffusion layer 25 can be increased.

  Further, according to the above configuration, the gas flow channel grooves constituting each groove group 34 intersect with the virtual straight line V orthogonal to the extending direction L of the gas flow channel grooves at three or more locations. The length of the gas channel groove in the existing direction L can be shortened while ensuring the channel length of the entire gas channel groove. As a result, the generated water W can be appropriately retained in the gas flow channel groove while increasing the flow rate of the oxidizing gas, and the humidity can be appropriately maintained.

Therefore, power generation performance can be improved.
(2) The separator 30 includes a plurality of groove groups 34.
When only one groove group 34 is formed in the separator 30, there is only one upstream portion 351 of the gas inflow channel groove 35, that is, an inlet portion communicating with the oxidizing gas supply hole 13. For this reason, if the number of gas flow channel grooves is excessively increased, the flow rate of the oxidizing gas in the gas flow channel grooves is rather slow, and there is a possibility that the amount of generated water staying in the gas flow channel grooves is large. As a result, power generation performance may be reduced.

  In this regard, according to the above configuration, since the separator 30 includes the plurality of groove groups 34, the number of gas inflow passage grooves 35 can be increased in proportion to the number of groove groups 34. For this reason, it can suppress that the flow velocity of the oxidizing gas in a gas flow path groove | channel becomes late | slow, and the production water which retains in a gas flow path groove | channel increases. Therefore, it is possible to suppress a decrease in power generation performance.

  (3) On the facing surface 31, the oxidizing gas from the oxidizing gas supply hole 13 is supplied to the upstream end 351 between each of the upstream ends 351 of the gas inlet passage grooves 35 in the plurality of groove groups 34 and the oxidizing gas supply hole 13. A common gas distribution groove 33 that distributes to each of the two is formed. Further, on the opposing surface 31, the gas from each of the downstream ends 362 is gathered between each of the downstream ends 362 of the gas outflow passage grooves 36 and the oxidizing gas discharge holes 15 in the plurality of groove groups 34 to collect the oxidizing gas. A common gas collecting groove 37 for discharging to the discharge hole 15 is formed.

  According to such a configuration, the oxidizing gas supplied from the oxidizing gas supply hole 13 is first introduced into the gas distribution groove 33 common to each groove group 34, and then the gas inflow path of each groove group 34 from the gas distribution groove 33. It is introduced into the groove 35.

  Further, the oxidizing gas discharged from the gas outflow passage groove 36 of each groove group 34 is discharged to the gas collecting groove 37 common to each groove group 34, and then discharged from the gas collecting groove 37 to the oxidizing gas discharge hole 15. The

  For this reason, compared with a configuration in which the upstream end 351 of the gas inflow channel groove 35 is directly connected to the oxidizing gas supply hole 13 and a configuration in which the downstream end 362 of the gas outflow channel groove 36 is directly connected to the oxidizing gas discharge hole 15. The structure of the path is simplified and the separator 30 can be reduced in size.

  (4) The gas inflow channel groove 35 and the gas outflow channel groove 36 are folded in the middle thereof. The gas inflow channel groove 35 is folded back so as to sandwich the folded portion 363 of the gas outflow channel groove 36.

  According to such a configuration, the generated water W can be actively retained in the bent portion or the downstream end 352 of the gas inflow passage groove 35 and the bent portion or the upstream end 361 of the gas outflow passage groove 36. Thereby, the humidity can be appropriately maintained by retaining the generated water W over a wide range of the groove group 34.

<Modification>
In addition, the said embodiment can also be changed as follows, for example.
As shown in FIG. 8, the groove group 34 is located as a gas flow path groove between the gas inflow path groove 35, the gas outflow path groove 36, and the gas inflow path groove 35 and the gas outflow path groove 36. In addition, two relay path grooves 131 in which both the upstream end and the downstream end are blocked may be provided. The gas inlet channel groove 35 extends along the extending direction L, and the gas outlet channel groove 36 extends along the extending direction L. Each of the relay channel grooves 131 extends along the extending direction L as a whole. In this case, a part of the oxidant gas that has flowed into the gas diffusion layer 25 on the cathode side from the gas inflow channel groove 35 and diffused flows out into the relay channel groove 131 and flows along the relay channel groove 131 and again diffuses the gas. It flows into the layer 25 and is diffused. For this reason, in addition to the downstream end 352 of the gas inflow passage groove 35 and the upstream end 361 of the gas outflow passage groove 36, the generated water W can be retained in the relay passage groove 131. Thereby, the humidity can be appropriately maintained by retaining the generated water W over a wide range of the groove group 34. Note that the number of the relay path grooves 131 may be one, or three or more. Similar changes can be made to the anode-side separator 40.

  As shown in FIG. 9, the folded portion 353 of the gas inflow passage groove 35 and the folded portion 363 of the gas outflow passage groove 36 may be formed so as not to be sandwiched between each other. Similar changes can be made to the anode-side separator 40.

  As shown in FIG. 10, the groove group 34 can be configured by the gas inflow channel groove 35 exemplified in the above embodiment and the gas outflow channel groove 36 exemplified in FIG. 8. Similar changes can be made to the anode-side separator 40.

The separators 30 and 40 are not limited to those made of press-formed metal thin plates, but may be made of cut carbon plates.
The gas distribution groove 33 may be omitted, and the upstream end 351 of the gas inflow channel groove 35 may be directly communicated with the oxidizing gas supply hole 13. The gas collecting groove 37 may be omitted, and the downstream end 362 of the gas outflow channel groove 36 may be directly communicated with the oxidizing gas discharge hole 15. The same change can be made for the separator 40 on the anode side.

  -The groove groups 34 and 44 can also be made into one.

  DESCRIPTION OF SYMBOLS 11 ... Power generation cell, 12 ... Membrane electrode assembly, 13 ... Oxidation gas supply hole, 14 ... Fuel gas supply hole, 15 ... Oxidation gas discharge hole, 16 ... Fuel gas discharge hole, 17 ... Cooling water supply hole, 18 ... Cooling Water discharge hole, 21 ... solid electrolyte membrane, 22 ... cathode side electrode layer, 23 ... anode side electrode layer, 24 ... catalyst layer, 25 ... gas diffusion layer, 30 ... separator, 31 ... facing surface, 32 ... connection groove, 33 ... Gas distribution groove, 34 ... Groove group, 35 ... Gas inflow path groove, 351 ... Upstream end, 352 ... Downstream end, 353 ... Folded part, 36 ... Gas outflow path groove, 361 ... Upstream end, 362 ... Downstream end , 363 ... folded portion, 37 ... gas collecting groove, 38 ... connection groove, 39 ... protrusion, 40 ... separator, 41 ... facing surface, 42 ... connection groove, 43 ... gas distribution groove, 44 ... groove group, 45 ... Gas inlet channel, 46 ... Gas outlet channel, 47 ... Gas Groove, 48 ... connecting groove 50 ... sealing frame, 51 to 54 ... support projections, 131 ... relay channel grooves.

Claims (9)

A separator disposed opposite to a gas diffusion layer of a membrane electrode assembly of a polymer electrolyte fuel cell,
A gas supply hole;
A gas exhaust hole;
A groove group formed of a plurality of gas flow channel grooves formed on a facing surface facing the gas diffusion layer and extending from the gas supply hole side toward the gas discharge hole side,
The groove group includes, as the gas flow channel groove, a single gas inflow channel groove whose upstream end communicates with the gas supply hole and whose downstream end is blocked; A gas outflow passage groove communicated with the gas discharge hole, and the gas passage groove intersects at three or more positions with respect to a virtual straight line intersecting with the extending direction of the gas passage groove.
Solid polymer fuel cell separator. Comprising a plurality of groove groups,
The separator for a polymer electrolyte fuel cell according to claim 1. The opposing surface has a common distribution of the reaction gas from the gas supply hole to each of the upstream ends between each of the upstream ends of the gas inflow passage grooves in the plurality of groove groups and the gas supply holes. Gas distribution grooves are formed,
On the opposite surface, the reaction gas from each of the downstream ends is gathered between each of the downstream ends of the gas outflow passage grooves in the plurality of groove groups and the gas discharge holes, and the gas discharge holes are collected. A common gas collecting groove for discharging is formed,
The polymer electrolyte fuel cell separator according to claim 2. The gas inflow channel groove is folded in the middle,
The separator for a polymer electrolyte fuel cell according to any one of claims 1 to 3. The entire gas inflow channel groove extends along the extending direction,
The separator for a polymer electrolyte fuel cell according to any one of claims 1 to 3. The gas outflow channel groove is folded in the middle,
The separator for a polymer electrolyte fuel cell according to any one of claims 1 to 5. The gas inflow channel groove is folded so as to sandwich the folded portion of the gas outflow channel groove,
The polymer electrolyte fuel cell separator according to claim 6. The entire gas outlet channel groove extends along the extending direction;
The separator for a polymer electrolyte fuel cell according to any one of claims 1 to 5. The groove group includes, as the gas flow channel groove, a relay channel groove that is located between the gas inflow channel groove and the gas outflow channel groove and is closed at both the upstream end and the downstream end.
The separator for a polymer electrolyte fuel cell according to any one of claims 1 to 8.

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