DE102020215416A1 - Electrochemical cell layer for a fuel cell stack - Google Patents

Abstract

The invention relates to an electrochemical cell layer (100) for a fuel cell stack of a fuel cell assembly, preferably for a fuel cell vehicle, having a polar plate (140; 142, 142; 142) and a membrane electrode device (110) provided thereon, the polar plate (140; 142, 142; 142) has at least one electrical contact device (151) for an electrical contact device (251) of cell voltage monitoring on/in its outer peripheral edge (150), and the contact device (151) has exactly or at least one electrical insulation (123 , 124).

Description

The invention relates to an electrochemical cell layer of a fuel cell assembly, preferably for a fuel cell vehicle. Furthermore, the invention relates to a fuel cell stack, a fuel cell, a fuel cell unit and a fuel cell system for a fuel cell vehicle.

State of the art

In a low-temperature polymer electrolyte fuel cell of a fuel cell unit z. B. a fuel cell system, for example. A fuel cell vehicle, there is an electrochemical conversion of two reactants of two operating media into electrical energy and heat. The fuel cell comprises at least one membrane-electrode unit, which has a layer structure of an ion- or proton-conducting membrane and catalytic electrodes (membrane-electrode unit with anode and cathode electrode as reactive layers) provided on both sides of the membrane. Furthermore, in particular a gas diffusion layer and/or a microporous particle layer is installed on both sides of the membrane-electrode unit (membrane-electrode device). As a rule, the fuel cell is formed with a multiplicity of membrane-electrode devices arranged in a stack and bipolar plates arranged between them (fuel cell stack).

Voltage monitoring of its individual cells (CVM: (single) cell voltage monitoring) is advantageous for operating a fuel cell. B. a cell monitoring plug strip with a large number of electrical contact devices, mostly pins (cf. 4 , Pin 251) electromechanically contacts the individual bipolar plates of the fuel cell. After the bipolar plates have been stacked, the connector strip is assembled by mechanically plugging the cell monitoring connector strip onto the electrochemical cell layers of the fuel cell. It is important that the pins are correctly inserted into the openings provided in the bipolar plates. If a pin erroneously gets between two bipolar plates instead of in the opening provided for this purpose, these bipolar plates are electrically short-circuited, which very quickly leads to a damaging temperature development when the fuel cell is started up.

task

It is an object of the invention to provide an improved fuel cell. In particular, it is an object of the invention to equip a fuel cell in such a way that an electrical contact device for a bipolar plate that has erroneously gotten between two bipolar plates does not cause an electrical short circuit between these bipolar plates. i.e. It is a process-reliable mechanical plugging of the electrical taps of the electrochemical cell layers of a fuel cell stack of the fuel cell with the given tolerances of the fuel cell stack (cell layers) and a cell monitoring plug, such. B. a cell monitoring power strip, be guaranteed.

Disclosure of Invention

The object of the invention is achieved by means of an electrochemical cell layer for a fuel cell stack of a fuel cell unit, preferably for a fuel cell vehicle, and by means of a fuel cell stack, a fuel cell, a fuel cell unit or a fuel cell system, in particular for a fuel cell vehicle. - Advantageous developments, additional features and / or advantages of the invention result from the dependent claims and the following description.

The cell layer according to the invention comprises a polar plate and a membrane electrode device provided thereon, the polar plate having at least one electrical contact device for an electrical contact device of cell voltage monitoring on/in its outer peripheral edge, and the contact device having exactly or at least one electrical insulation on the side of its connector face . The polar plate can have the electrical insulation in at least one area on its contact device in such a way that a contact of the polar plate is electrically isolated from a contact device of the cell voltage monitoring that is foreign to this cell layer.

i.e. incorrect plugging in of the contact device which is foreign to this cell layer cannot lead to an electrical short circuit between this and a cell layer directly adjacent to it in the fuel cell stack. If it is plugged in incorrectly, the contact device that is not used for this cell layer will not find its correct place on/in the cell layer directly adjacent to the cell layer and could electrically short-circuit these two adjacent cell layers in the fuel cell stack without the electrical insulation according to the invention (cf. 5 ). However, according to the invention, a drop in performance of a relevant fuel cell and a temperature development damaging the fuel cell can be avoided.

Between the polar plate and a membrane-electrode unit of the membrane-electrode device, an anode space, preferably with a gas diffusion layer and/or a microporous particle layer, or a cathode space, preferably with a gas diffusion layer and/or a microporous particle layer, is set up within the cell layer. This anode space or cathode space is not described in detail here and can be designed according to the prior art or otherwise according to future developments. A cathode space or anode space relating to this cell layer can be set up analogously between this cell layer and a polar plate of a directly adjacent electrochemical cell layer of the fuel cell stack. - The contact device is preferably essentially freely accessible for the contact device in the insertion direction of the contact device.

The outer peripheral edge of the polar plate is formed on the one hand by the outer peripheral section running at least partially around the polar plate (direction of thickness extension) and on the other hand by those two peripheral surface sections (direction of surface extension) that extend somewhat inwards from the outer peripheral section onto the two large sides of the polar plate. If a complete outer peripheral edge were cut out of the polar plate, the result would be a structure with the outer contour of the polar plate and an inner contour similar to the outer contour but smaller. A respective large-area side of the polar plate merges into the outer peripheral edge, i. H. a respective peripheral surface section coincides with an outer peripheral edge of the relevant large-surface side.

The electrical insulation can be provided outside on the outer peripheral edge in the area of the contact device. Furthermore, the electrical insulation can essentially completely cover the contact device on precisely/at least one side or precisely/at least two sides. Furthermore, the electrical insulation can protrude beyond the contact device on exactly/at least one side or exactly/at least two sides.

The electrical insulation can be permanently and in particular detachably or non-detachably connected to the polar plate. Furthermore, the electrical insulation can be materially connected to the polar plate, in particular glued. Furthermore, the electrical insulation can be positively and/or non-positively connected to the polar plate, in particular plugged together. In particular, if the polar plate is inseparably connected to the electrical insulation, the contact device or the pin cannot simply push the electrical insulation aside; accordingly, a potential short circuit is avoided.

The membrane electrode device can be set up in a sealing collar (often also referred to as a (sub)gasket), with an edge, in particular an outer edge, of the sealing collar forming the electrical insulation. Here are in a fuel cell stack z. B. local, one-sided electrical insulation of the polar plates by means of the respective sealing sleeve of the membrane electrode devices possible, for which purpose in an area of the contact devices, in particular of contact pins, the voltage monitoring, the sealing sleeves z. B. are locally firmly attached to the polar plates. An external adhesive for the sealing sleeves or a hot-melt adhesive for the sealing sleeves themselves can be used for the material connection.

The sealing sleeve can have a sealing section on and/or off the membrane electrode device. Furthermore, the sealing collar can have a transition section between the membrane electrode device, in particular its sealing section, and its electrical insulation. Furthermore, the electrical insulation of the grommet may have an overhang portion as a free end portion protruding beyond the polar plate.

The sealing section preferably merges integrally into the transition section. Furthermore, the transition section preferably transitions integrally into the electrical insulation of the sealing sleeve. The transition section preferably has an S-shaped kink or an S-shaped, rounded course, which bridges the height of a seal (see below) for the electrical insulation, so that this can be firmly connected to the polar plate.

A seal (often also referred to as a sealing) can be set up between the polar plate relating to the membrane-electrode device and its sealing sleeve. Furthermore, a second seal (again often referred to as a sealing) can be set up on the sealing collar away from the polar plate relating to the membrane-electrode device. The seals are preferably set up above and below the sealing section of the sealing collar, preferably aligned in the vertical direction of the fuel cell stack. These seals serve as a fluid seal for a media supply, media disposal (cooling medium (flowing/outflowing), cathode operating medium/exhaust gas medium and/or anode operating medium/exhaust gas medium) and the relevant anode space or cathode space in the fuel cell stack.

The polar plate can have exactly one contact device or at least two, in particular exactly two, contact devices. Furthermore, can the contact device can be designed as a contact device going into a plane of the polar plate. Furthermore, the or the at least one contact device can be designed as an opening, a socket, a pin or a tab. In addition, the contact device can be materially connected in one piece to the polar plate or can be formed integrally with the polar plate.

The cell layer can have an anode space or a cathode space between its polar plate and a membrane-electrode assembly of its membrane-electrode device. The anode space or the cathode space can be internally delimited by a gas diffusion layer and/or a microporous particle layer. Furthermore, the cell layer can have, apart from its polar plate, a gas diffusion layer and/or a microporous particle layer for a cathode space or an anode space.

The polar plate can be designed as a component part (monopolar plate) of a bipolar plate, as a bipolar plate or as a monopolar plate. The cell layer is preferably designed as a solid composite of the polar plate and the membrane electrode device installed in the sealing sleeve. Furthermore, the cell voltage monitoring for the cell layer is preferably designed as an individual cell voltage monitor.

character list

• 1 in einem vereinfachten Blockschaltbild eine Ausführungsform eines Brennstoffzellenaggregats für ein Brennstoffzellensystem eines Brennstoffzellenfahrzeugs, gemäß der Erfindung,
• 2 in einer explodierten Perspektivansicht eine elektrochemische Zelllage, die eine Bipolarplatte und eine einseitig daran vorsehbare Membran-Elektroden-Einrichtung aufweist,
• 3 einen zweidimensionalen Ausschnitt der erfindungsgemäßen Zelllage aus 2 in einem Bereich ihrer elektrischen Kontakteinrichtung für eine Zellspannungsüberwachung des Brennstoffzellenaggregats,
• 4 einen zweidimensionalen Ausschnitt eines erfindungsgemäßen Brennstoffzellenstapels in einem Bereich seiner elektrischen Kontakteinrichtungen für die Zellspannungsüberwachung, und
• 5 einen zweidimensionalen Ausschnitt eines Brennstoffzellenstapels ohne die Erfindung in einem Bereich seiner elektrischen Kontakteinrichtungen für die Zellspannungsüberwachung.

The invention is explained in more detail below using exemplary embodiments with reference to the attached schematic drawing, which is not true to scale. In the case of the invention, a feature can be positive, ie present, or negative, ie absent. In this specification, a negative feature is not explicitly explained as a feature unless emphasis is placed on its absence according to the invention. i.e. the invention actually made and not constructed by the prior art is to omit this feature. The absence of a feature (negative feature) in an embodiment indicates that the feature is optional. - Show in the merely exemplary and schematic figures (Fig.) Of the drawing:

• 1 in a simplified block diagram an embodiment of a fuel cell unit for a fuel cell system of a fuel cell vehicle according to the invention,
• 2 an exploded perspective view of an electrochemical cell layer that has a bipolar plate and a membrane electrode device that can be provided on one side,
• 3 a two-dimensional section of the cell layer according to the invention 2 in an area of their electrical contact device for cell voltage monitoring of the fuel cell aggregate,
• 4 a two-dimensional section of a fuel cell stack according to the invention in an area of its electrical contact devices for cell voltage monitoring, and
• 5 a two-dimensional section of a fuel cell stack without the invention in an area of its electrical contact devices for cell voltage monitoring.

Embodiments of the invention

The invention is based on exemplary embodiments of three embodiments ( 3 : Embodiments one and two, 4 : Embodiment three) of an electrochemical cell layer 100 and a fuel cell stack 10 of a fuel cell of a fuel cell assembly 1 for a low-temperature polymer electrolyte fuel cell system of a fuel cell vehicle, ie a motor vehicle having a fuel cell or a fuel cell system, explained in more detail.

Only those sections of the fuel cell system which are necessary for an understanding of the invention are shown in the drawing. Although the invention is described and illustrated in detail by preferred embodiments, the invention is not limited by the disclosed embodiments. Other variations can be devised without departing from the scope of the invention.

the 1 shows the fuel cell assembly 1 according to a preferred embodiment, with at least one, in particular a plurality of individual fuel cells 11 (individual cells 11) bundled to form a fuel cell stack 10, also referred to as a fuel cell, which are accommodated in a preferably fluid-tight stack housing 16. Each individual cell 11 comprises an anode compartment 12, preferably with a gas diffusion layer and a microporous particle layer, and a cathode compartment 13, preferably with a gas diffusion layer and a microporous particle layer, which are spatially and electrically separated from one another by a membrane of a membrane-electrode unit 15.

A bipolar plate 140; 142, 142 (plate assembly, flow field plate) arranged, which serves, among other things, for supplying/removing operating media 3, 5 into an anode space 12 of a first individual cell 11 and a cathode space 13 of a second individual cell 11 directly adjacent thereto and also realizes an electrically conductive connection between these individual cells 11. The fuel cell unit 1 has an anode supply 20 and a cathode supply 30 to supply the fuel cell with its actual operating media 3 (anode operating medium, actual fuel), 5 (cathode operating medium, usually air).

The anode supply 20 includes in particular: a fuel reservoir 23 for the anode operating medium 3 (inflow); an anode supply path 21 having an ejector 24; an anode off-gas path 22 for an anode off-gas medium 4 (outflowing, mostly into the environment 2); preferably a fuel recirculation line 25 with a fluid delivery device 26 located therein and possibly a water separator.

The cathode supply 30 includes in particular: a cathode supply path 31 for the cathode operating medium 5 (flowing, mostly from the environment 2), with preferably a fluid delivery device 33; a cathode exhaust gas path 32 for a cathode exhaust gas medium 6 (outflowing, mostly into the environment 2) with preferably a turbine 34, possibly that of an exhaust gas turbocharger; preferably a moisture transmitter 36; possibly a wastegate 35 between the cathode supply path 31 and the cathode exhaust gas path 22; and, if necessary, a water separator.

The fuel cell assembly 1 also includes in particular a cooling medium supply 40 through which the fuel cell preferably by means of their bipolar plates 140; 142, 142 (cooling medium paths 42) can be integrated into a cooling circuit in a heat-transferring manner for temperature control. The cooling medium supply 40 comprises a cooling medium inflow path 41 and a cooling medium outflow path 43. The cooling medium 7 (flowing in), 8 (flowing out) circulating in the cooling medium supply 40 is preferably conveyed by means of at least one cooling medium conveying device 44 Fuel cell unit 1 peripheral system components such. B. a control unit, which can be one of the fuel cell vehicle itself.

the 2 shows an example of a single electrochemical cell layer 100 of the fuel cell stack 10, having a single bipolar plate 140 (also known as a polar plate 140) and a single membrane-electrode device 110 that can be provided on it. The membrane-electrode device 110 comprises a membrane-electrode unit 15 as well as devices, such as a gas diffusion layer and/or a microporous particle layer, etc., for their anode space 12 and their cathode space 13, which can be sealed by seals 130 (see below).

In the present case, two monopolar plates 142, 142 (also referred to as polar plates 142), in particular two materially one-piece or integral monopolar plates 142, 142, are combined to form a two-part or materially one-piece bipolar plate 140 (also referred to as polar plate 140). It is of course possible to design a one-piece bipolar plate 140 (also referred to as a polar plate 140) as a one-piece or integral material. Furthermore, instead of using a bipolar plate 140, the invention can also be implemented using a single monopolar plate 142 (which can also be referred to as a polar plate 142).

The bipolar plate 140; 142, 142 (cf. also the 3 and 4 ) on/in its outer peripheral edge 150 (cf. above) at least one electrical contact device 151 for an electrical contact device 251 ( 4 ) of cell voltage monitoring. According to the invention, the contact device 151 has electrical insulation 123, 124 fixed there on its mating face, preferably laterally on its mating face. In particular, the bipolar plate 140; 142, 142 the electrical insulation 123, 124 in such a way that the bipolar plate 140; 142, 142 is electrically insulated from a contact device 251 of cell voltage monitoring that is foreign to this cell layer 100. - In the 3 two alternative contact devices 151 are shown, on the one hand a socket 151 (solid, also 4 ) and on the other hand a pin 151 (dashed).

Here shows the 3 at the top an electrical insulation 123, 124 for the socket 151, formed as an electrically insulating material layer 123 along a peripheral surface section (direction of surface extension) of the bipolar plate 140; 142, 142, and towards its free end as a bent insulating material layer 124 a short distance along an outer peripheral portion (direction of thickness extension) of the bipolar plate 140; 142, 142. Furthermore, the 3 below an electrical insulation 123, 124 for the pin 151, formed as an electrically insulating material layer 123 along a peripheral surface section (direction of surface extension) of the bipolar plate 140; 142, 142, and further in this direction as insulating material layer 124 z. B. via a free end of the bipolar plate 140; 142, 142 out.

the 4 shows an integration of the invention in a sealing sleeve 120 for the membrane-electrode device 110 of the cell layer 100. Here, fun an edge 123, 124, in particular an outer edge 123, 124, of the sealing sleeve 120 yaws as electrical insulation 123, 124. Which of the in 2 illustrated edges of the sealing sleeve 120 for this purpose depends on the circumstances of the fuel cell stack 10 . In principle, all four in the 2 illustrated edges of the sealing collar 120 come into question.

In an area around the outer edge 123 , 124 of the sealing sleeve 120 , the latter initially has a sealing section 121 starting from the membrane electrode device 110 . The sealing section 121 preferably has two external seals 130 which are set up to seal a media supply, a media disposal and/or a relevant anode space 12 or cathode space 13 . The sealing section 121 transitions into a preferably S-shaped transition section 122, which extends the level of the sealing sleeve 120 to the level of an outside of the bipolar plate 140; 142, 142 brings.

The transition section 122 merges into a free end section of the sealing sleeve 120 as electrical insulation 123, 124. Here, the electrical insulation 123 is fixed to the outside of the bipolar plate 140; 142, 142 connected, which z. B. by means of an external adhesive for the sealing collar 120 or preferably by a hot-melt adhesive of the sealing collar 120 can be done. Furthermore, this section 123 is followed by the electrical insulation 123, 124, free from the bipolar plate 140; 142, 142 protruding overhang portion 124 (electrical insulation 124) of the electric insulation 123, 124 on.

the 5 shows, analogous to 4 , which can happen if the electrical insulation 123, 124 according to the invention is missing. If a contact device 251 is plugged in incorrectly, the contact device 251 can get between two bipolar plates 140 directly adjacent to one another and electrically short-circuit them in the fuel cell stack 10, which has the known consequences.

Claims (10)

Electrochemical cell layer (100) for a fuel cell stack (10) of a fuel cell unit (1), preferably for a fuel cell vehicle, with a polar plate (140; 142, 142; 142) and a membrane electrode device (110) provided thereon, the polar plate ( 140; 142, 142; 142) on/in its outer peripheral edge (150) has at least one electrical contact device (151) for an electrical contact device (251) of a cell voltage monitor, characterized in that the contact device (151) on its connector face exactly or at least has electrical insulation (123, 124). Electrochemical cell layer (100) according to the preceding claim, characterized in that the polar plate (140; 142, 142; 142) has the electrical insulation (123, 124) in a region on its contact device (151) such that a contact of the polar plate ( 140; 142, 142; 142) is electrically isolated from a contact device (251) of the cell voltage monitoring that is external to this cell layer (100). Electrochemical cell layer (100) according to one of the preceding claims, characterized in that the electrical insulation (123, 124): • is provided in the area of the contact device (151) outside on the outer peripheral edge (150), • the contact device (151) on exactly / covers at least one side or exactly/at least two sides essentially completely, and/or • protrudes beyond the contact device (151) on exactly/at least one side or exactly/at least two sides. Electrochemical cell layer (100) according to one of the preceding claims, characterized in that the electrical insulation (123, 124): • is firmly and in particular detachably or non-detachably connected to the polar plate (140; 142, 142; 142), • to the polar plate (140; 142, 142; 142) is materially connected, in particular glued, and/or • is positively and/or non-positively connected to the polar plate (140; 142, 142; 142), in particular plugged together. Electrochemical cell layer (100) according to one of the preceding claims, characterized in that the membrane electrode device (110) is set up in a sealing collar (120), wherein an edge, in particular an outer edge, of the sealing collar (120) the electrical insulation (123, 124). Electrochemical cell layer (100) according to one of the preceding claims, characterized in that: • the sealing sleeve (120) on and/or apart from the membrane electrode device (110) has a sealing section (121), • the sealing sleeve (120) between the membrane electrode device (110), in particular its sealing section (121), and its electrical insulation (123, 124) has a transition section (122), and/or • the electrical insulation (123, 124) of the sealing collar (120) an overhang portion (124) as has a free end portion projecting beyond the polar plate (140; 142, 142; 142). Electrochemical cell layer (100) according to one of the preceding claims, characterized in that a seal (130) is set up between the polar plate (140; 142, 142; 142) relating to the membrane electrode device (110) and its sealing collar (120). , and/or a second seal (130) is installed on the sealing sleeve (120) away from the polar plate (140; 142, 142; 142) relating to the membrane electrode device (110). Electrochemical cell layer (100) according to one of the preceding claims, characterized in that: • the polar plate (140; 142, 142; 142) has exactly one contact device (152) or at least two, in particular exactly two, contact devices (152), • the The contact device (152) is designed as a contact device (152) extending into a plane of the polar plate (140; 142, 142; 142), • the or the at least one contact device (152) as an opening (152), a socket (152) , a pin or a tab is formed, and/or • the contact device (152) is integrally connected to the polar plate (140; 142, 142; 142) or is formed integrally with the polar plate (140; 142, 142; 142). Electrochemical cell layer (100) according to one of the preceding claims, characterized in that: • the cell layer (100) between its polar plate (140; 142, 142; 142) and a membrane-electrode unit (15) of its membrane-electrode device (15) has an anode compartment (12) or a cathode compartment (13), • the anode compartment (12) or the cathode compartment (13) is internally delimited by a gas diffusion layer and/or a microporous particle layer, • the cell layer (100) apart from its polar plate (140; 142, 142; 142) has a gas diffusion layer and/or a microporous particle layer for a cathode space (13) or an anode space (12), and/or • the polar plate (140; 142, 142; 142) as a component part ( 142) a bipolar plate (140), as a bipolar plate (140; 142, 142) or as a monopolar plate (142). Fuel cell stack (10), fuel cell, fuel cell assembly (1) or fuel cell system for a fuel cell vehicle, with a plurality of electrochemical cell layers (100), characterized in that an electrochemical cell layer (100) or essentially all of the electrochemical cell layers (100) according to one of the preceding claims is formed.

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