CN116802859A

CN116802859A - Distributor plate for an electrochemical cell, electrochemical cell and method for producing a distributor plate

Info

Publication number: CN116802859A
Application number: CN202180088365.2A
Authority: CN
Inventors: J·H·奥斯; V·施勒佩尔; S·克伦格
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-10-29
Filing date: 2021-10-05
Publication date: 2023-09-22
Also published as: WO2022089893A1; DE102020213576A1

Abstract

The invention relates to a distributor plate (7) for an electrochemical cell (1), wherein the distributor plate (7) has a structure comprising a parting bead (12) and a main channel (11), the parting bead each having a surface (13), and the surface (13) of the parting bead (12) having a secondary channel (15), wherein the secondary channels (15) each have an end region (25) in which the depth (27) of the secondary channel (15) decreases in the direction towards the closest main channel (11) and/or the width (29) of the secondary channel (15) increases in the direction towards the closest main channel (11). The invention further relates to an electrochemical cell (1) and to a method for producing a distributor plate (7).

Description

Distributor plate for an electrochemical cell, electrochemical cell and method for producing a distributor plate

Technical Field

The invention relates to a distributor plate for an electrochemical cell, wherein the distributor plate has a structure comprising parting strips and a main channel, the parting strips each having a surface. Furthermore, the invention relates to an electrochemical cell and a method for manufacturing a distributor plate.

Background

Electrochemical cells are electrochemical energy converters and are known in the form of fuel cells or electrolysers.

The fuel cell converts chemical reaction energy of the continuously supplied fuel and oxidant into electric energy. In known fuel cells, in particular hydrogen (H ₂ ) And oxygen (O) ₂ ) Converted into water (H) ₂ O), electrical energy and heat.

In particular, proton exchange membrane (Proton Exchange Membrane =pem) fuel cells are known. Proton exchange membrane fuel cells have a centrally disposed membrane that is permeable to protons, i.e., hydrogen ions. The oxidizing agent, in particular oxygen in air, is thereby spatially separated from the fuel, in particular hydrogen.

The fuel cell has an anode and a cathode. The fuel is supplied to the fuel cell at the anode and is catalytically oxidized to protons with release of electrons, which reach the cathode. The released electrons are conducted away from the fuel cell and flow to the cathode via an external circuit.

An oxidant, in particular oxygen in air, is supplied to the fuel cell at the cathode and reacts to water by absorbing electrons and protons from the external circuit. The water thus produced is led out of the fuel cell. The total reaction is:

O ₂ +4H ⁺ +4e ^- →2H ₂ O

here, a voltage is present between the anode and the cathode of the fuel cell. In order to increase this voltage, a plurality of fuel cells can be arranged mechanically in succession in a fuel cell stack, also referred to as a galvanic pile or fuel cell structure, and electrically connected in series.

The stack of an electrochemical cell typically has end plates that compress the individual cells against each other and impart stability to the stack. The end plates can also be used as the positive and/or negative poles of the stack for conducting the current.

The electrodes, i.e., anode and cathode, and the membrane can be structurally combined into a Membrane Electrode Assembly (MEA), also known as Membrane Electrode Assembly.

The stack of electrochemical cells also has bipolar plates, also known as gas distributor plates or distributor plates. The bipolar plates serve to uniformly distribute the fuel to the anode and to uniformly distribute the oxidant to the cathode. Furthermore, bipolar plates generally have a surface structure, in particular a channel-like structure, for distributing fuel and oxidant to the electrodes. In particular in fuel cells, channel-like structures are also used for the removal of water produced during the reaction. Additionally, the bipolar plate can have a structure for transporting a cooling medium through the electrochemical cell to conduct heat away.

In addition to the medium guidance in oxygen, hydrogen and water, bipolar plates ensure planar electrical contact with the membrane.

For example, a fuel cell stack typically comprises up to several hundred individual fuel cells, which are stacked one on top of the other in layers, so-called sandwiches. These single fuel cell cells have an MEA and have bipolar plate halves on the anode side and on the cathode side, respectively. The fuel cell unit comprises, in particular, an anode unipolar plate and a cathode unipolar plate, typically in the form of stamped sheet materials, respectively, which together form a bipolar plate and thus form channels for guiding gases and liquids, and between which channels a cooling medium flows.

In addition, electrochemical cells typically include a gas diffusion layer for gas distribution. The gas diffusion layer is arranged between the bipolar plate and the MEA and is typically composed of a carbon fiber nonwoven fabric also known as "gas diffusion backing (gas diffusion backing)" (GDB) on the channel side, i.e. in the direction towards the adjoining bipolar plate, and a microporous layer also known as "micro porous layer" (MPL) on the catalyst side, i.e. in the direction towards the membrane.

In contrast to fuel cells, the electrolysis device is an energy converter, which preferably breaks down water into hydrogen and oxygen when a voltage is applied. The electrolysis device also has, inter alia, an MEA, bipolar plates and gas diffusion layers.

It is particularly important for the efficiency of an electrochemical cell, in particular an electrochemical cell having a polymer electrolyte membrane, that the electrode layers arranged on the membrane are uniformly supplied with the reaction gas.

The known distributor plates have, in particular, channels and corresponding adjoining or adjacent parting strips, which form a structure. The Channels are also called main Channels or passages (Channels), and the division bars are also called Lands (Lands). The surface of the spacer bar that is at least partially parallel to the plane of extension of the distributor plate comprises the contact surface of the distributor plate with the gas diffusion layer of the adjoining electrochemical cell. The gases, i.e. hydrogen and oxygen, pass from the channels of the distributor plate via the gas diffusion layer to the reaction zone on the membrane. The regions of the gas diffusion layer lying against the spacers of the distributor plate and thus the corresponding regions of the MEA lying therebelow are relatively poorly supplied with reactant gases, in particular under the conditions of flooding of the electrochemical cell, which may lead to an undesirable uneven current density distribution.

On the side of the membrane on which air, i.e. oxygen, is supplied, water is produced during operation of the fuel cell, which water must be transported through the gas diffusion layer to the channels of the distributor plate and removed therefrom from the cell. Typical operating temperatures for electrochemical cells with membranes are less than 120 ℃, such that water is typically condensed and present in liquid form in the gas diffusion layer. In the gas diffusion layer, the transport direction of water is opposite to that of gas, and accumulated water can seriously hinder replenishment of reaction gas, particularly oxygen.

The higher the power density of the electrochemical cell, the more water is produced, so that the transport of liquid water in the contact area between the gas diffusion layer and the air channel side of the distributor plate may be insufficient.

JP2020-47441A describes an improved drainage system for bipolar plates in which additional grooves are provided in the flanks of the parting strips parallel to the direction of the main channel.

JP2020-47443A describes a bipolar plate with improved drainage, wherein the parting strips of the bipolar plate have an additional channel system which is arranged transversely to the direction of the main channel. Each two channels of the additional channel system have a common outflow. Furthermore, a transverse structure in the main channel of the distributor plate is disclosed, which results in a high pressure loss.

JP2020-47440A likewise relates to a bipolar plate with an improved drainage system, wherein the parting bead has indentations transversely to the direction of the main channel and additional grooves are present along the flanks of the parting bead parallel to the direction of the main channel.

Disclosure of Invention

A distributor plate for an electrochemical cell is proposed, wherein the distributor plate has a structure comprising a parting bead and a main channel, wherein the parting bead has a surface, respectively, and the surface of the parting bead has a secondary channel, wherein the secondary channels have end regions, respectively, in which the depth of the secondary channel decreases in the direction towards the closest main channel and/or the width of the secondary channel increases in the direction towards the closest main channel, in particular in the main flow direction in the main channel. Preferably, the secondary channel is arranged with a first portion at a first angle in the range of 30 ° to 150 ° with respect to the primary channel and with a second portion at a second angle in the range of less than 45 ° with respect to the primary channel.

Furthermore, an electrochemical cell comprising the distributor plate and a method for manufacturing the distributor plate are proposed, the method comprising at least the following steps:

a. a planar member is provided which is configured to be positioned in a substantially planar relationship,

b. in particular by embossing and/or using a laser, sub-channels are produced on the planar component, and

c. the main channel is formed by the planar member such that a distributor plate is formed.

Preferably, step b is performed before step c.

The electrochemical cell, preferably a fuel cell or an electrolysis device, preferably comprises at least one distributor plate, at least one gas diffusion layer and at least one membrane or membrane electrode assembly. In particular, gas diffusion layers are respectively arranged between the distributor plate and the membrane.

The gas diffusion layer preferably has a porous structure and further preferably bears against the distributor plate at a high pressure of about 10bar to 15 bar. The membrane is preferably a polymer electrolyte membrane, which is also referred to as proton exchange membrane or Proton Exchange Membrane (PEM), and which contains or consists of, for example, perfluorosulfonic acid (PFSA), in particular Nafion (r). In addition, alkaline membranes can also be used.

Preferably, the gas diffusion layer comprises a nonwoven, in particular a carbon fiber nonwoven, and optionally a microporous layer, wherein the nonwoven is arranged on the side of the gas diffusion layer facing the distributor plate. It is further preferred that the gas diffusion layer comprises a carbon fiber nonwoven fabric and, if necessary, a microporous layer. In the case of nonwoven fabrics, the gas permeability in the thickness direction, i.e. in the direction towards the membrane, can be comparable to the gas permeability in the plane, i.e. in the direction parallel to the membrane.

Preferably, the distributor plate comprises carbon such as graphite, a metal such as stainless steel or titanium and/or an alloy containing the metal. Further preferably, the distributor plate is constructed of carbon, metal and/or alloy. In particular, the base plate of the distributor plate is composed of carbon, metal and/or alloy.

The secondary channels can also be referred to as drainage channels, capillary channels, grooves or as microscopically small, groove-like structures and serve to channel the formed reaction water into the primary channels. The secondary channels are arranged in particular on the side of the distributor plate that is directed towards the adjacently arranged gas diffusion layers in the electrochemical cell. The at least one secondary channel preferably connects two main channels, in particular two adjacent main channels. The at least one secondary channel can also terminate with a first end on the parting bead, in particular in the contact area, while the second end terminates in the nearest primary channel end. The expression "in the direction towards the closest main channel" is to be understood as the direction along the secondary channel from the parting bead, in particular the contact area, to the end area. The distributor plate, which can also be referred to as bipolar plate, preferably has a wave-like structure, wherein the parting strips and the main channels are alternately and further preferably respectively arranged parallel to each other.

Preferably, the surfaces of the parting strips each comprise at least one contact region, which can also be referred to as a contact surface, against which the adjacently arranged gas diffusion layers rest. Preferably, the contact area of the division bar is arranged substantially parallel to the bottom surface of the main channel. "substantially parallel" is to be understood as follows: the plane in which the contact area is located encloses an angle of less than 30 °, more preferably less than 20 °, even more preferably less than 10 ° and in particular less than 5 °, with the bottom surface.

Due to the porous structure of the gas diffusion layer, the natural outflow of water, which is typically present in liquid form, becomes difficult at high current densities, so that water accumulation can occur. This water accumulation can limit the power density of the electrochemical cell in the contact area.

Preferably, the division bar has a side face, which is in particular comprised by the surface of the division bar. It is further preferred that the surface of the spacer bar comprises two sides for each spacer bar, which sides respectively engage to the bottom surfaces of adjacent main channels. The flanks can also be referred to as flanks and are preferably arranged at a flank angle relative to the floor, wherein the flank angle is further preferably in the range of 90 ° to 135 °, in particular in the range of 95 ° to 125 °. Furthermore, the side faces are preferably arranged in a bent manner relative to the contact region. The sides can be flat or at least partially rounded. Preferably, the bottom surface is at least partially planar.

It is further preferred that the secondary channels are each arranged at least partially on the side face. Furthermore, the side faces are preferably arranged in a bent manner relative to the contact area, which can also be referred to as contact surface. Preferably, the secondary channel is arranged in the contact area and further preferably extends beyond the contact area at least to the side.

The main channel preferably has a bottom surface, wherein the end regions of the secondary channels are arranged on the sides of the spacer bars or on the bottom surface of the main channel, respectively. Preferably, the bottom surfaces of the corresponding adjacent primary channels are joined to the surfaces of the spacer bars.

The sides of the division bar are typically arranged between the contact area of the division bar and the bottom surface of the adjacent main channel. If the secondary channel extends only to the side of the division bar, the end region is preferably arranged on the side. If the secondary channel extends from the contact area via the side of the parting bead to the nearest bottom surface of the primary channel, the end area of the secondary channel is preferably arranged on the bottom surface of the primary channel.

The end regions form the transition between the essentially planar bottom surface of the secondary channel and the primary channel, wherein the bottom surface is preferably unstructured except for the end regions.

At least one of the sub-channels can also open into the end structure in the end region, wherein the sub-channel branches into at least two sub-channels in the end structure and each has a smaller diameter, in particular a smaller width and/or depth, than the sub-channel. In particular, the respective dimensions of the cross-sections of the at least two sub-channels are smaller than the dimensions of the cross-sections of the sub-channels. "diameter" is understood to mean in particular the largest diameter of the cross section. The end structure can also be referred to as a finer structure or expansion, effectively expanding the surface of the liquid water, enabling improved drainage of the liquid water and/or better volatilization of the liquid water into the guided gas phase in the main channel. It is further preferred that the end structure has at least three sub-channels, wherein at least one sub-channel can branch into further, at least two further sub-channels. The sub-channel and at least one of said sub-channels preferably partly enclose an angle in the range of 20 ° to 70 °, more preferably in the range of 30 ° to 60 °, for example 45 °. Furthermore, the at least two sub-channels preferably terminate in an orientation substantially parallel to the sub-channels.

Preferably, the first part of the respective secondary channel, in particular in the contact region, is arranged substantially orthogonally to the primary channel, in particular to at least one adjacent primary channel, so that a section of as short as possible for the drainage of water is obtained. "substantially orthogonal" is understood to mean that the first angle is 60 ° to 120 °, further preferably 80 ° to 100 ° and particularly preferably 85 ° to 95 °.

Preferably, the second portion of the respective secondary channel is arranged substantially parallel to the primary channel, in particular, at least one adjacent primary channel. By "substantially parallel" is understood that the second angle is less than 30 °, further preferably less than 20 °, more preferably less than 10 ° and especially preferably less than 5 °.

Due to the arrangement at the second angle, in particular in the vicinity of the end region, the secondary channel is oriented in the main flow direction of the air in the main channel.

The end region can also be referred to as a disengagement region. In the end region, the water droplets are discharged from the secondary channel into the primary channel, and the water droplets are detached from the secondary channel.

Preferably, the secondary channels each have a curved course at least on the sides of the division bar. Alternatively or additionally, the secondary channel can have a straight course on the side, which has at least one, preferably more than one, change of direction, which can also be referred to as a bend. The secondary channels run substantially orthogonally to the primary channels in the contact region, whereas preferably the direction of the secondary channels approaches the direction of the (Angleichung) primary channels before the end regions. This approximation is preferably performed on a curved path. The direction of travel of the secondary channel is changed from a direction at a first angle to a direction at a second angle relative to the primary channel.

Preferably, the first portions of the secondary channels each have a straight course.

The main channels are preferably straight and are further preferably arranged parallel to each other on the distributor plate. The secondary channel has a cross-section which is preferably triangular, i.e. V-shaped, round, square or polygonal. Preferably, the cross-section of the secondary channel is V-shaped. The cross-section of the secondary channel can be constant over the length of the secondary channel, in particular up to but not including the end region, or can vary in size and/or geometry. The cross-section of the primary channel is preferably larger than the cross-section of the secondary channel, at least fifty times larger.

Preferably, in the end region, the depth of the respective secondary channel decreases in the direction toward the closest main channel and the width increases in the direction toward the closest main channel, in particular in the main flow direction. Further preferably, the depth decreases continuously and/or the width increases continuously. The depth preferably decreases until the level of the floor is reached and the secondary channel thus ends. The maximum width of the secondary channel in the end region is preferably the same as the width of the primary channel, in particular with respect to the bottom surface of the primary channel.

Preferably, the width and/or depth of the secondary channels in the first portion is 1 μm to 150 μm, further preferably 1 μm to 100 μm, particularly preferably 1 μm to 50 μm, more preferably 1 μm to 10 μm, particularly preferably 1 μm to 6 μm, respectively. Preferably, the gas diffusion layer arranged adjacent to the distributor plate comprises fibres, and further preferably the width of the secondary channels is smaller than the fibre diameter of the gas diffusion layer, which for example is about 8 μm. The width of the secondary channels can also be greater than the fiber diameter of the gas diffusion layer. In particular, the width of the sub-channel can be selected according to the structure of the adjacent gas diffusion layers, and the depth can be selected accordingly.

Furthermore, in particular the depth and width of the secondary channels are selected such that the secondary channels form a capillary effect, in particular in the case of water.

Preferably, the distributor plate is at least partially coated. The coating can be more hydrophilic or more hydrophobic than the material of the substrate of the distributor plate. In particular, a coating may be applied to the surface of the spacer bar in order to reduce the electrical contact resistance of the distributor plate. Furthermore, the coating can completely cover the surface of the division bar and, if necessary, also the main channel, or can be present locally.

The coating can be hydrophobic and can have, in particular, a lotus effect. By "hydrophobic" is preferably understood that the wettability is inferior to that of steel with a smooth surface with water, more preferably the contact angle with respect to the water droplet is greater than 70 °, in particular greater than 80 °. The coating is present in particular in the contact region, in order here, for example, to reduce the contact resistance. Furthermore, a coating can be present on the bottom surface. For example, in particular a hydrophobic coating can be present on the bottom surface, and the secondary channels can be uncoated.

Preferably, the coating comprises carbon, in particular carbon particles, such as carbon black or graphite, and comprises in particular an organic binder, for example synthetic resin and/or polyvinylidene fluoride (PVDF). The binder can be thermoplastic or thermosetting. The coating preferably has a layer thickness in the range from 1nm to 200 μm, more preferably in the range from 5nm to 100 μm, particularly preferably in the range from 5nm to 50 μm, in particular in the range from 5nm to 50 nm. In the contact area of the spacer, a layer thickness of more than 5 μm is preferably present. The layer thickness is preferably less than 1 μm on the sides and the bottom.

Furthermore, the distributor plate can have a hydrophilic coating at least in part. In particular the end regions, have a hydrophilic coating. By "hydrophilic" is preferably understood that the wettability is better than that of steel with a smooth surface with water, more preferably the contact angle with respect to water droplets is less than 40 °, in particular less than 10 °. Hydrophilic surfaces can be produced, for example, by microscopic roughening. Furthermore, the coating can have an internal structuring, and the at least one secondary channel can be formed by the internal structuring.

The contact area of the spacer bar can be hydrophobic or hydrophilic. If the contact area is hydrophilic, water accumulates directly in the contact area, in particular by wetting and/or condensation, and is then transported away into the main channel via the at least one secondary channel. If the contact area is hydrophobic, the water condenses in the gas diffusion layer and directly in the at least one secondary channel and is then transported away into the primary channel, in particular into the adjacent primary channel.

The coating can comprise hydrophilic components, such as oxidized carbon particles having hydroxide groups, carbonyl groups and/or carboxyl groups, with polymer binders, which can be used in particular for carbon distributor plates. Preferably, the coating has a surface roughness Ra in the range of 0.1 μm to 10 μm, and further preferably has a maximum peak-to-valley distance (bulk peak-to-valley maximum distance) in the range of 0.1 μm to 20 μm, more preferably in the range of 1 μm to 10 μm.

The coating can be applied, for example, by laser sintering, or can be applied by the following method: the method is also used to apply metal, ceramic, polymer or mixtures thereof in a pattern to a distributor plate. Another example of a coating method is spray coating.

Alternatively, it is also possible to first apply a coating material, such as a powder, to the distributor plate, which is removed locally in a targeted manner, for example again, from the contact region, and then to carry out a selective (laser) sintering process. Thus, for example, only the main channel can be provided with a coating. The coating can be performed selectively, for example by masking and/or screen printing.

The coating can also be applied in a planar manner and then removed partially, for example by laser or mechanical means, so that the secondary channels are exposed and in particular the side walls of the secondary channels are formed from the coating.

The secondary channels can be introduced into the base plate of the distributor plate, in particular of a sheet material, and/or into the coating of the distributor plate. In the latter case mentioned, the layer thickness is preferably greater than 5 μm.

Especially if the secondary channels are introduced into the base plate of the distributor plate, the secondary channels can be introduced into the base plate, for example by embossing under high pressure, before a larger area of deformation of the base plate is performed to form the primary channels through which air and/or coolant is guided.

The secondary channels can also be applied by means of a laser, in particular by targeted material evaporation.

Advantages of the invention

By means of the distributor plate according to the invention, the transport of the reaction products produced, in particular liquid water, from the contact area between the gas diffusion layer and the distributor plate on the air channel side of the distributor plate of the electrochemical cell is assisted and simplified. The electrochemical cell can thus be operated at a higher current density and thus at a higher power.

Due to the small dimensions of the secondary channels running essentially transversely to the contact area of the primary channels between the gas diffusion layer and the distributor plate, the transport of the reaction water is accelerated by capillary forces. By a first angle in the range of 30 ° to 150 °, a transport path of the water on the parting bead and in particular in the contact area is achieved that is as short as possible. By virtue of the reduced width of the sub-channels in particular, the gas diffusion layers, in particular the fibers of the gas diffusion layers, cannot penetrate into the sub-channels, so that water in the sub-channels can flow under the gas diffusion layers unimpeded.

Furthermore, by means of the special geometry of the secondary channel, in particular by means of the end region and optionally by means of a second angle in the range of less than 45 °, it is possible that water droplets are formed and are blown out of the secondary channel by the air flowing in the primary channel and then purged by the air flow along the primary channel. Through the end region, water leaves the secondary channel into the primary channel and can be blown away as microscopic droplets through the primary channel, and through the orientation of the end region in the direction of the primary channel, the air flow in the primary channel can push the generated droplets out of the secondary channel.

Due to capillary effect, water in the contact area is sucked into the secondary channel and evenly distributed within the secondary channel. The removal of water from the secondary channel is assisted by the end regions of the secondary channel, in particular in the primary channel, in such a way that water flows out of the contact region in the secondary channel until again a uniform distribution or steady state is achieved. The end regions of the embodiment according to the invention thus ensure that the secondary channels are continuously emptied and liquid water is carried away from the contact region between the gas diffusion layer and the distributor plate.

The coating can further improve the escape of water droplets from the secondary channel into the primary channel in that it aids in the diffusion of water in the end region and thus provides a greater active surface for the air flow. The coating in the main channel can reduce the adhesion of the water droplets and thus improve the transport of the formed droplets.

Drawings

Embodiments of the present invention are explained in more detail with reference to the drawings and the following description.

The drawings show:

fig. 1 is a schematic diagram of an electrochemical cell according to the prior art.

Fig. 2 is a fuel cell construction with a distributor plate.

Fig. 3 is a contact area between a gas diffusion layer and a distributor plate.

Fig. 4 is a contact area between a gas diffusion layer and a distributor plate having sub-channels.

Fig. 5 is a section of a distributor plate with a curved, running secondary channel.

Fig. 6 is an end region of the secondary channel.

Detailed Description

In the following description of embodiments of the invention, identical or similar elements are denoted by the same reference numerals, wherein repeated descriptions of these elements are omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

Fig. 1 schematically shows an electrochemical cell 1 according to the prior art in the form of a fuel cell. The electrochemical cell 1 has a membrane 2 as an electrolyte. The membrane 2 separates the cathode chamber 39 from the anode chamber 41.

In the cathode chamber 39 and the anode chamber 41, an electrode layer 3, a gas diffusion layer 5, and a distributor plate 7 are disposed on the membrane 2, respectively.

The distributor plate 7 has a main channel 11 for gas supply to the gas diffusion layer 5, for example air 43 in the cathode chamber 39 and hydrogen 45 in the anode chamber 41 to the gas diffusion layer 5. On the distributor plate 7, the main channels 11 alternate with the parting strips 12.

On the surface 13 of the parting bead 12, contact areas 47 are formed between the distributor plate 7 and the adjacently arranged gas diffusion layers 5, respectively. Furthermore, the division bar 12 has side faces 31 and the main channel 11 has a bottom face 33.

Fig. 2 shows a fuel cell structure comprising a plurality of distributor plates 7 and a membrane electrode assembly 4 comprising a membrane 2. Oxygen 43 or air with oxygen 43 contained therein and hydrogen 45 are directed to the membrane electrode assembly 4 through the distributor plate 7. The water 51 is discharged in the main channel 11 of the distributor plate 7, into which the oxygen 43 or the air in which the oxygen 43 is contained is fed. Furthermore, the distributor plate 7 serves for guiding the coolant 49.

Fig. 3 shows the contact area 47 between the gas diffusion layer 5 and the distributor plate 7 in the electrochemical cell 1. The main channel 11 is shown having a bottom surface 33 and the spacer 12 (adjacent to the bottom surface 33) having a surface 13 has side surfaces 31. A portion of the surface 13 of the parting bead 12 forms a contact area 47.

Fig. 4 shows a part of the contact area 47 between the gas diffusion layer 5 and the distributor plate 7 with the secondary channels 15. The gas diffusion layer 5 is arranged on the distributor plate 7. In the secondary channel 15 without the gas diffusion layer 5, the water 51 accumulates and can flow away unhindered.

Fig. 5 shows a partial plan view of the distributor plate 7 with the secondary channels 15, which have a curved course at the transition from the first portion 17 to the second portion 21 of the secondary channels 15.

The first portions 17 of the secondary channels 15 are each arranged at a first angle 19 with respect to the primary channel 11 having a primary flow direction 53. The second portion 21 of the secondary channel 15 is arranged at a second angle 23 with respect to the primary channel 11 and the primary flow direction 53, respectively.

Furthermore, the secondary channel 15 has an end region 25 which merges into the primary channel 11, so that droplets of water 51 escape from the secondary channel 15 into the primary channel 11.

Fig. 6 shows an end region 25 of the secondary channel 15. In the embodiment presented, the secondary channel 15 has a V-shaped cross section 35. The secondary channel 15 has a reduced depth 27 in the end region 25 and an increased width 29 in the end region 25. By means of the altered geometry of the secondary channel 15 in the end region 25, the air flowing through is provided with an enlarged water surface and is more accessible to the water surface than in the case of a narrow secondary channel 15, in particular if the secondary channel 15 is not completely filled. Due to the friction between the air flowing through and the water surface, in the end region 25 the water 51 is pressed further out of the secondary channel 15 and the water 51 blocked in the secondary channel 15 is detached from the secondary channel 15 in the form of droplets and is entrained in the main flow direction 53 of the main channel 11. The end region 25 can have a coating 37, for example, in order to assist in the expansion of the water surface at a given filling level of the secondary channel 15 in the end region 25 or/and in the detachment process of the water droplets into the primary channel 11.

The present invention is not limited to the embodiments described herein and the aspects emphasized therein. Rather, various modifications which are within the framework of actions of the person skilled in the art are possible within the scope given by the claims.

Claims

1. A distributor plate (7) for an electrochemical cell (1), wherein the distributor plate (7) has a structure comprising parting strips (12) and a main channel (11), the parting strips each having a surface (13), and the surfaces (13) of the parting strips (12) having sub-channels (15),

wherein the secondary channels (15) each have an end region (25) in which the depth (27) of the secondary channel (15) decreases in the direction toward the closest main channel (11) and/or the width (29) of the secondary channel (15) increases in the direction toward the closest main channel (11).

2. Distributor plate (7) according to claim 1, characterized in that the secondary channel (15) is arranged with a first portion (17) at a first angle (19) in the range of 30 ° to 150 ° with respect to the primary channel (11) and with a second portion (21) at a second angle (23) in the range of less than 45 ° with respect to the primary channel (11).

3. The distributor plate (7) according to any one of the preceding claims, wherein the division bar (12) has a side face (31) and the secondary channels (15) are each at least partially arranged on the side face (31).

4. A distributor plate (7) according to claim 3, characterized in that the main channel (11) has a bottom surface (33) and that the end regions (25) of the secondary channels (15) are arranged on the sides (31) of the parting bead (12) or on the bottom surface (33) of the main channel (11), respectively.

5. Distributor plate (7) according to claim 3 or 4, characterized in that the secondary channels (15) each have a curved course at least on the sides (31) of the parting bead (12).

6. Distributor plate (7) according to any one of the preceding claims, wherein the width (29) and/or depth (27) of the secondary channel (15) in the first portion (17) is 1 μm to 150 μm, respectively, and in particular the cross section (35) of the secondary channel (15) is V-shaped.

7. The distributor plate (7) according to any one of the preceding claims, wherein the distributor plate (7) has at least in part a coating (37), in particular a hydrophobic coating (37).

8. Distributor plate (7) according to claim 7, characterized in that the secondary channels (15) are introduced into the coating (37).

9. Electrochemical cell (1) comprising a distributor plate (7) according to any one of claims 1 to 8.

10. A method for manufacturing a dispenser plate (7) according to any one of claims 1 to 8, comprising at least the steps of:

a. providing a planar component (8),

b. the secondary channel (15) is produced on the planar component (8), in particular by embossing and/or using a laser, and

c. the main channel (11) is formed by the planar element (8) such that the distributor plate (7) is formed.