Search

DE-102019113903-B4 - Fuel cell separator

DE102019113903B4DE 102019113903 B4DE102019113903 B4DE 102019113903B4DE-102019113903-B4

Abstract

Fuel cell separator with: a plate-shaped conductive separator body (6) designed to be arranged between membrane electrode assemblies (1) in a fuel cell; and Recesses (7) and projections (8) which are formed in the separator body (6) such that the recesses (7) and the projections (8) are arranged alternately parallel to each other, characterized in that the projections (8) comprise first projections (8) which are arranged to face an electrode layer (4, 5) of the membrane electrode assembly (1), a thin film (9, 11) is arranged on a surface of each of the first projections (8), wherein the thin film (9, 11) has a higher conductivity than the separator body (6), the first projections (8) are arranged to be in contact with the electrode layer (4, 5) of the membrane electrode assembly (1) with the thin films (9, 11) located between them, the depressions (7) comprise first depressions (7) that open in a projection direction of the first projections (8), each of the first depressions (7) is arranged to form a passage (10, 12) through which oxidation gas or fuel gas is supplied to the electrode layer (4, 5) of the membrane electrode assembly (1), the passage (10, 12) being located on an inner side of each of the first depressions (7), and a section of each of the thin films (9, 11) that is in contact with the electrode layer (4, 5) of the membrane electrode assembly (1), a groove (13, 14) comprising the groove (13, 14) extending in a direction that intersects the recesses (7) and the projections (8) and is connected to at least one of the passages (10, 12) located on opposite sides of one of the first projections (8) that encompasses the thin film (9, 11).

Inventors

  • Satoshi Kawabe

Assignees

  • TOYOTA BOSHOKU KABUSHIKI KAISHA

Dates

Publication Date
20260513
Application Date
20190524
Priority Date
20180528

Claims (5)

  1. Fuel cell separator comprising: a plate-shaped conductive separator body (6) designed to be arranged between membrane electrode assemblies (1) in a fuel cell; and recesses (7) and projections (8) formed in the separator body (6) such that the recesses (7) and the projections (8) are arranged alternately parallel to each other, characterized in that the projections (8) comprise first projections (8) which are configured to face an electrode layer (4, 5) of the membrane electrode assembly (1), a thin film (9, 11) is arranged on a surface of each of the first projections (8), wherein the thin film (9, 11) has a higher conductivity than the separator body (6), the first projections (8) are configured to be in contact with the electrode layer (4, 5) of the membrane electrode assembly (1) with the thin films (9, 11) located between them, the recesses (7) comprise first recesses (7) which open in a projection direction of the first projections (8), each of the first recesses (7) is configured to to form a passage (10, 12) through which oxidation gas or fuel gas is supplied to the electrode layer (4, 5) of the membrane electrode assembly (1), wherein the passage (10, 12) is located on an inner side of each of the first depressions (7), and a section of each of the thin films (9, 11) that is in contact with the electrode layer (4, 5) of the membrane electrode assembly (1) comprises a groove (13, 14), wherein the groove (13, 14) extends in a direction that intersects the depressions (7) and the projections (8), and is connected to at least one of the passages (10, 12) that are located on opposite sides of one of the first projections (8) that comprises the thin film (9, 11).
  2. Fuel cell separator according to Claim 1 , characterized in that the groove (13, 14) has an end in a longitudinal direction of the groove (13, 14), the end being connected to the passage (10, 12).
  3. Fuel cell separator according to Claim 2 , characterized in that the groove (13, 14) is one of a plurality of grooves (13, 14) which are spaced apart from each other in a direction in which the projections (8) extend, and those of the grooves (13, 14) which are adjacent to each other in the direction in which the projections (8) extend are connected to different passages (10, 12) which are located on opposite sides of the corresponding first projection (8).
  4. Fuel cell separator according to Claim 1 , characterized in that the groove (13, 14) has opposite ends in a longitudinal direction of the groove (13, 14), wherein one of the opposite ends is connected to one of the passages (10, 12) located on opposite sides of the corresponding first projection (8), and the other of the opposite ends is connected to the other of the passages (10, 12) located on opposite sides of the corresponding first projection (8).
  5. Fuel cell separator according to one of the Claims 1 until 4 , characterized in that the thin film (9, 11) has a higher hydrophilicity than the separator body (6).

Description

background 1. Area The following description concerns a fuel cell separator. 2. Description of the state of the art Japanese patent no. JP 6 199 266 B2 Disclosure reveals a fuel cell comprising a membrane electrode assembly (MEA) and two separators that hold the MEA between them in the thickness direction. The membrane electrode assembly comprises an electrolyte film, an anode electrode layer, and a cathode electrode layer. The cathode electrode layer is bonded to one of the opposite faces of the electrolyte film in the thickness direction. The anode electrode layer is bonded to the other opposite face of the electrolyte film in the thickness direction. In a fuel cell, separators divide the membrane electrode assemblies and arrange the membrane electrode assemblies between them in the thickness direction as described above. As in 5 As shown schematically, typical separators 51 each comprise a separator body 53, recesses 54, and projections 55. The separator body 53 is arranged between membrane electrode units 52 (electrolyte film 61, anode electrode layer 57, and cathode electrode layer 58) and is conductive. The recesses 54 and the projections 55 are configured in the separator body 53 such that the recesses 54 and projections 55 are arranged alternately parallel to each other. The surface of each projection 55 comprises a thin film 56 with a higher conductivity than the separator body 53. The projections 55 are each in contact with the anode electrode layer 57 or the cathode electrode layer 58 of the membrane electrode unit 52 with the intervening thin films 56. The separator body 53 includes a passage 59 formed in the inner side of each recess 54 located between the projections 55 facing the anode electrode layer 57 of the membrane electrode assembly 52. The passage 59 is configured to supply fuel gas, such as hydrogen, to the anode electrode layer 57. The separator body 53 also includes a passage 60 formed in the inner side of each recess 54 located between the projections 55 facing the cathode electrode layer 58 of the membrane electrode assembly 52. The passage 60 is configured to supply oxidation gas, such as air, to the cathode electrode layer 58. In the fuel cell, when fuel gas is supplied to the anode electrode layer 57 and oxidation gas is supplied to the cathode electrode layer 58, the fuel gas reacts with the oxidation gas in the membrane electrode assembly 52, thereby generating power. The reaction also produces water in the cathode electrode layer 58. The water produced in this way is discharged from the fuel cell using the flow of oxidation gas in the passage 60. The reaction of fuel gas with oxidation gas in the membrane electrode assembly 52 is influenced by an electrical resistance between the membrane electrode assembly 52 and the separator body 53. To reduce the increase in electrical resistance, a thin film 56 is formed on the surface of each projection 55 in the separator body 53. In separator 51, the ones on one side (bottom side in) 5 The projections 55 of the separator body 53, located in the thickness direction, are in contact with the cathode electrode layer 58 of the membrane electrode assembly 52 and the thin films 56 located between them. Thus, when power generation produces water in the cathode electrode layer 58, the water is easily retained between the cathode electrode layer 58 and the thin films 56. Consequently, the water generated in the cathode electrode layer 58 cannot be completely removed from the fuel cell by the flow of oxidation gas. This can cause water to accumulate near the cathode electrode layer 58. The accumulation of water near the cathode electrode layer 58 limits the contact of oxidation gas with the cathode electrode layer 58. As a result, oxidation gas is not completely distributed throughout the membrane electrode assembly 52, thus impairing the reaction of fuel gas with oxidation gas. The separator 51 contains the projections 55, which are located on the other side (upper side in 5 The thin films 6 of the separator body 53 are located in the thickness direction and are in contact with the anode electrode layer 57 of the membrane electrode assembly 52. If a certain amount of moisture is contained in the thin films 56 of the separator 51, the increase in the electrical resistance of the thin films 56 is slightly reduced. Thus, if the membrane electrode assembly 52 is made thinner, water generated in the cathode electrode layer 58 can pass through the electrolyte film 61. and move towards the anode electrode layer 58. In this case, if water is contained in the thin films 56 that are in contact with the anode electrode layer 57 of the membrane electrode assembly 52 in the separator 51, an increase in electrical resistance in the thin films 56 can be slightly reduced. However, if the water is retained between the thin films 56 and the anode electrode layer 57 in greater quantities than necessary, so that the water accumulates excessively near the anode el