DE102015224178A1 - Redox fuel cell system - Google Patents

Abstract

The invention relates to a redox fuel cell system comprising: a fuel cell stack of at least one redox fuel cell having an anode and a cathode separated by an ion selective separator, wherein the fuel cell stack is configured to pass a fuel and a catholyte solution, and a regenerator stack a plurality of regenerator plates for the regeneration of the catholyte solution, wherein the regenerator stack is designed for passing the catholyte solution and an oxidizing fluid, wherein the fuel cell stack and the regenerator stack are arranged one above the other or side by side and braced by a common bracing system.

Description

The invention relates to a redox fuel cell system. In particular, the invention relates to a unit of at least one redox fuel cell and a regenerator of the redox fuel cell system. Furthermore, the invention shows a method for producing this unit.

Fuel cell systems for mobile applications such as motor vehicles are known in the art. In its simplest form, a fuel cell is an electrochemical energy converter that converts fuel and oxidant into reaction products, producing electricity and heat. For example, hydrogen is used as the fuel and air or oxygen as the oxidizing agent in such a fuel cell. The gases are fed into corresponding diffusion electrodes, which are separated by a solid or liquid electrolyte. The electrolyte transports charged ions between the two electrodes.

In an indirect or redox fuel cell system, the oxidizer does not react directly at the cathode. Rather, a reduced form of redox molecule (catholyte) reacts at a location spaced from the cathode to be oxidized. This oxidized form of the redox molecule is then fed to the cathode. Such a redox fuel cell system is considered here and is, for example, in DE 10 2013 217 858 A1 described.

Redox fuel cells are also distinguished from redox flow batteries, in which the cathode and the anode are supplied with a catholyte or anolyte, the i.d.R. stored in appropriate containers. Both subsystems are therefore operated indirectly. In the presently considered redox fuel cell system, however, the fuel is stored in a pressure vessel and fed directly to the anode. The oxidizer supplied to the regenerator, i.d.R. Air, however, is not stored in a container.

According to the prior art, the regenerator is connected as an independent component via fluid lines with the redox fuel cell. As a rule, the regenerator consists of repetitive regenerator plates which form a regenerator stack. Furthermore, two end plates and a clamping system are provided. The regenerator stack is clamped by means of the Verspannsystems between the two end plates.

It is an object of the present invention to provide a redox fuel cell system, which has a relatively low volume and a relatively low weight, is easy to manufacture and can be operated permanently. It is another object of the invention to provide a corresponding method for producing the redox fuel cell system.

The object is achieved by the features of the independent claims. The dependent claims have advantageous embodiments of the invention the subject.

The technology disclosed herein includes a redox fuel cell system having a regenerator and at least one redox fuel cell. The redox fuel cell comprises an anode and a cathode, which are separated in particular by an ion-selective separator. There is provided a supply for a fuel to the anode. In other words, during operation of the redox fuel cell, the anode is in fluid communication with a fuel reservoir.

Preferred fuels for the redox fuel cell system are: hydrogen, low molecular weight alcohol, biofuels, or liquefied natural gas. The cathode has, for example, a supply for a catholyte solution (also: POM) to the cathode. The ion-selective separator can be designed, for example, as a proton exchange membrane (PEM). Preferably, a cation-selective polymer electrolyte membrane is used. Materials for such a membrane include Nafion ^®, Flemion ^® and Aciplex ^®.

The above object is achieved by a redox fuel cell system comprising a fuel cell stack and a regenerator stack:
The fuel cell stack comprises at least one redox fuel cell. The redox fuel cell in turn has an anode and a cathode. Anode and cathode are separated by an ion-selective separator. Usually, the anode and the cathode are arranged in or on bipolar plates. In the simplest case, the fuel cell stack thus comprises two bipolar plates with an anode and a cathode and the separator. Preferably, however, it is provided that the individual plate-shaped components of a plurality of redox fuel cells are combined in the fuel cell stack. In particular, in the bipolar plates, the corresponding recesses are provided to direct the fuel to the anode and the catholyte solution to the cathode.

The regenerator stack includes multiple regenerator plates. For example, these are embossed steel plates. Between and / or in the regenerator plates, the catholyte solution is combined with the oxidation fluid (in particular oxygen or air).

Cooling lines can be provided both in the fuel cell stack and in the regenerator stack.

According to the invention, it is provided that the fuel cell stack and the regenerator stack are arranged one above the other (1st exemplary embodiment) or next to each other (second exemplary embodiment) and braced by means of a common bracing system. Compared to the prior art, there are therefore no longer two separate stacks with two bracing systems, but a common stack with a common bracing system. This results in a smaller construction volume and a reduced number of components. Furthermore, the thermal mass of the entire redox fuel cell system is reduced.

Since both components, the fuel cell stack and the regenerator stack, high-voltage components, they can be protected and monitored together in one unit due to the inventive arrangement. According to the invention, reduction and oxidation take place within a bracing system. The catholyte solution required for this purpose must therefore be moved only within one clamping system. This allows a simple and secure design of a closed circuit for the catholyte solution. For example, a common housing may be used. Certain sensors for monitoring no longer have to be arranged separately for the regenerator stack and the fuel cell stack, but can be shared.

It is preferably provided that the fuel cell stack and / or the regenerator stack do not have their own clamping system, but are braced only via the common bracing system. So there is only one clamping system.

Another advantage of the common clamping system is that only two end plates are needed. Thus, it is preferably provided that the unit of fuel cell stack and regenerator stack comprises two common end plates. When the fuel cell stack and the regenerator stack are stacked (1st embodiment), the first end plate abuts the fuel cell stack and the second end plate abuts the regenerator stack. When the fuel cell stack and the regenerator stack are arranged side by side (2nd embodiment), both end plates abut the fuel cell stack and the regenerator stack.

The regenerator stack and the fuel cell stack are thus located between the two end plates. The clamping system acts on the two end plates, so as to clamp the unit.

The term "end plate" here always means the endplate system with all its components and functions. Part of an end plate can be, for example, media inlets and media outlets. The functions of the end plate include, for example, ensuring sufficient stability and sealing functions.

It is preferably provided that in at least one of the two end plates, a media input and / or a media outlet is formed. The medium is, for example, the fuel, the catholyte solution, the oxidation fluid or a cooling fluid. The corresponding medium can be present as a liquid or gas.

It is preferably provided that in the first end plate, a supply and / or a return for the fuel is formed.

It is preferably provided that a supply line and / or a discharge line for the oxidation fluid is formed in the second end plate.

As already described, the regenerator stack and the fuel cell stack can be arranged side by side (2nd embodiment). It is preferably provided that in at least one of the end plates, a cavity, for example a channel, is formed, through which a media exchange is possible. In particular, an exchange of the catholyte solution between regenerator stack and fuel cell stack takes place through this cavity. It is provided that the cavity extends through the end plate from the regenerator stack to the fuel cell stack, so that the media exchange is completely possible in the respective end plate and the medium does not have to be performed outside of the end plate. In addition, it is of course also possible to integrate in the end plates media inputs or media outputs to guide a medium to the outside.

Preferably, when the two stacks are arranged one above the other (1st exemplary embodiment), a middle plate is provided between the fuel cell stack and the regenerator stack. Preferably, the center plate is for sealing between the regenerator stack and the fuel cell stack. In addition, the use of the center plate increases the stability of the entire unit.

Preferably, the center plate is configured for media exchange between the fuel cell stack and the regenerator stack. In particular, the catholyte solution is exchanged through the middle plate. This is located in the central plate preferably a first fluid conduit for guiding the catholyte solution from the fuel cell stack into the regenerator stack and / or a second fluid conduit for guiding the catholyte solution out of the regenerator stack in the fuel cell stack.

Particularly preferably, a pump device for conveying the catholyte solution is integrated in the middle plate. In particular, while the housing of the pump, for example, the volute, an integral part of the center plate.

Alternatively, the pumping device for conveying the catholyte solution may also be integrated into the first or second end plate. In this case, it is advisable to guide the fluid line associated with the pump device at least in places through the bracing system, outside the bracing system or through a housing surrounding the bracing system in order to ensure a connection between the regenerator stack and the fuel cell stack.

The redox fuel cell system preferably comprises a cooling circuit for the fuel cell stack and / or a cooling circuit for the regenerator stack. The at least one pump for the at least one cooling circuit is preferably integrated in one of the two end plates or the middle plate.

Advantageously, it is provided that a Regeneratorbypassventil is arranged in the second end plate or the middle plate. Via the regenerator bypass valve, catholyte solution can be diverted into a reservoir. Alternatively, the Regeneratorbypassventil be integrated, for example, in the Verspannsystem.

Particularly preferably, the reservoir for the catholyte solution is integrated into the middle plate.

As described, it is advantageously provided that the catholyte solution circulates only over the middle plate between the two stacks. The reservoir for the catholyte solution is advantageously also integrated in the middle plate or is located in or on the bracing system. This creates a compact unit that can be closed with a high-voltage-proof housing. Within this unit, the reduction and the oxidation proceed. The catholyte solution is only moved in this unit.

It is preferably provided that the bracing system comprises at least one bracket, bands, plates or tie rods. The bracing system and engages the fuel cell stack and regenerator stack at least in places. The bracing system is preferably made of steel and / or fiber-reinforced plastic.

The redox fuel cell system is advantageously used in a motor vehicle. The drive of the motor vehicle is supplied with electrical energy via the redox fuel cell system.

The invention further includes a method for producing the described redox fuel cell system. In the method, stacking takes place of a redox fuel cell and the regenerator plates, wherein the fuel cell stack and the regenerator stack are clamped by a common bracing system.

The subclaims and advantageous embodiments described in the context of the redox fuel cell system accordingly find advantageous application to the method according to the invention.

Further details, features and advantages of the invention will become apparent from the following description and the figures. Show it:

1 a schematic view of a prior art redox fuel cell system,

2 1 is a schematic view of a redox fuel cell system according to the invention according to a first embodiment,

3 a schematic view of the redox fuel cell system according to the invention according to a variant of the first embodiment, and

4 a schematic view of a redox fuel cell system according to the invention according to a second embodiment.

1 shows a redox fuel cell system 1 According to the state of the art. By the feed 10 Fuel, in this case hydrogen, enters an anode 2 a redox fuel cell 13 , About a return 20 Excess fuel is removed. The anode 2 is through a separator 4 , here designed as a proton exchange membrane PEM, from a cathode 3 separated. At anode 2 and cathode 3 is a power tap 5 intended. 1 shows only a redox fuel cell 13 , Usually, however, several of these redox fuel cells 13 strung together.

On the anode side, hydrogen is oxidized as in conventional fuel cells. The protons pass through the separator 4 in the area of cathode 3 , The cathode 3 is via a fluid line system (with first fluid line 11 and second fluid line 12 ) with a regenerator 6 (also: regenerator stack 6 ) connected. From the regenerator 6 exiting regenerated catholyte solution Lox with an increased proportion of oxidized redox molecules passes through the second fluid line 12 to the cathode 3 , There, the catholyte solution L is at least partially reduced. At the same time she picks up the protons. The reduced catholyte solution Lred then passes through the first fluid line 11 in the regenerator 6 ,

In the regenerator 6 the catholyte solution is regenerated. Ie. the redox molecules are again oxidized as much as possible and also release the protons. It creates a cycle, driven by the pumping device 8th in which at least parts of the catholyte solution L are continuously reduced and oxidized.

A major oxidation fluid delivery unit 7 promotes oxidizing fluid via a supply line 21 , here oxygen or air, in the regenerator 6 , As a reaction product, water or water vapor leaves the regenerator 6 , Downstream of the regenerator 6 is a derivative 22 and a fluid catcher 9 arranged. The fluid collecting device 9 is designed here as a condenser and separates water from the outflowing gases.

2 shows a redox fuel cell system 1 according to the first embodiment. The redox fuel cell system 1 includes a fuel cell stack 16 with several stacked redox fuel cells 13 ,

Over the fuel cell stack 16 there is a regenerator stack 6 from several regenerator plates 14 , The regenerator plates 14 are arranged parallel to the plate-shaped components of the redox fuel cells (for example, the bipolar plates).

On both sides of the unit from the fuel cell stack 16 and the regenerator stack 6 There are two end plates 17 . 18 , The first end plate 17 is the fuel cell stack 16 assigned. The second end plate 18 is the regenerator stack 6 assigned.

Between the regenerator pile 6 and the fuel cell stack 16 there is a middle plate 19 ,

The unit of regenerator stack 6 and fuel cell stacks 16 including the two end plates 17 . 18 and the center plate 19 , is with a bracing system 15 braced. Through the tension system 15 acts a force according to the drawn tension direction 23 to this unit. The tension direction 23 stands perpendicular to the regenerator plates 14 and the plate-shaped components of the redox fuel cell 13 ,

That of the main oxidation fluid delivery unit 7 incoming supply line 21 is in the second end plate 18 educated. Furthermore, the to the fluid collecting device 9 leading derivative 22 in the second end plate 18 educated. Alternatively, the supply line 21 and / or the derivative 22 also laterally, for example by the Verspannsystem 15 be guided.

In the first end plate 17 are the feed 10 and the return 20 formed of the fuel. Alternatively, the feed 10 and / or the return 20 also laterally, for example by the Verspannsystem 15 be guided.

In a further preferred alternative is provided, the supply line 21 and / or the derivative 22 and / or the feed 10 and / or the return 20 over the middle plate 19 respectively.

2 further shows that the first fluid line 11 for guiding the catholyte solution L from the fuel cell stack 16 in the regenerator stack 6 in the center plate 19 is trained. The first fluid line 11 connects here directly and directly the fuel cell stack 16 with the regenerator stack 6 over the middle plate 19 ,

Also the second fluid line 12 for guiding the catholyte solution L out of the regenerator stack 6 in the fuel cell stack 16 is in the center plate 19 arranged. In the first embodiment, the pumping device 8th in the middle plate 19 integrated.

3 shows the redox fuel cell system 1 according to a variant of the first embodiment. Here is an example of the second fluid line 12 shown that the guidance of a medium, in this case the catholyte solution, not necessarily on the end plates 17 . 18 or center plate 19 must pass, but also through the clamping system 15 is possible. As an alternative to the illustrated variant, the corresponding medium can also be outside the bracing system 15 be guided.

According to 3 leads the second fluid line 12 through the middle plate 19 , about the clamping system 15 to the first end plate 17 , The pumping device 8th is here in the bracing system 15 integrated. Alternatively, the pumping device could 8th also outside the bracing system 15 or in the first end plate 17 to be ordered.

In the examples shown, the pumping device is located 8th in the second fluid line 12 , Alternatively or additionally, the pumping device could 8th for the catholyte solution also in the first fluid line 11 to be ordered.

4 shows the second embodiment. Identical or functionally identical components are provided with the same reference numerals in all embodiments. In the second embodiment, the two stacks 6 . 16 arranged side by side. Accordingly, the two end plates 17 . 18 each at the fuel cell stack 16 and regenerator stacks 6 at. For the sake of clarity, the media guides, pumps and reservoirs are not shown here. However, also in the second embodiment in the two end plates 17 . 18 such elements are integrated. The replacement of the catholyte solution L advantageously took place via the free space between the two stacks 6 . 16 so that here too the catholyte solution circulates within the one clamping system.

Not shown in the figures are any cooling circuits. Pumps for these cooling circuits can also be used in the endplates 17 . 18 or the center plate 19 to get integrated.

LIST OF REFERENCE NUMBERS

1

 Redox fuel cell system

100

Redox fuel cell system according to the prior art

2

 anode

3

 cathode

4

 separator

5

 current tap

6

 Regeneratorstapel

7

 Main oxidizing fluid delivery unit

8th

 pumping device

9

 Fluid collecting device (condenser)

10

supply

11

first fluid line

12

second fluid line

13

Redox fuel cell

14

Regeneratorplatten

15

clamping system

16

fuel cell stack

17

first end plate

18

second end plate

19

center plate

20

return

21

supply

22

derivation

23

the bracing direction

L

 catholyte

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013217858 A1 [0003]

Claims (10)

Redox fuel cell system ( 1 ), comprising: a fuel cell stack ( 16 ) from at least one redox fuel cell ( 13 ) with an anode ( 2 ) and a cathode ( 3 ) separated by an ion-selective separator ( 4 ) are separated, wherein the fuel cell stack ( 16 ) is designed to pass a fuel and a catholyte solution (L), and • a regenerator stack ( 6 ) of several regenerator plates ( 14 ) for the regeneration of the catholyte solution (L), wherein the regenerator stack ( 6 ) is designed for passing through the catholyte solution (L) and an oxidizing fluid, wherein the fuel cell stack ( 16 ) and the regenerator stack ( 6 ) are arranged one above the other or side by side and via a common bracing system ( 15 ) are braced. Redox fuel cell system according to claim 1, characterized in that the fuel cell stack ( 16 ) and / or the regenerator stack ( 6 ) do not have their own clamping system, but only via the common bracing system ( 15 ) are braced. Redox fuel cell systems according to one of the preceding claims, characterized in that the unit of fuel cell stack ( 16 ) and regenerator stack ( 6 ) two common end plates ( 17 . 18 ), wherein the bracing system ( 15 ) for clamping the unit on the two end plates ( 17 . 18 ), preferably in at least one of the two end plates ( 17 . 18 ) a media input ( 10 . 21 ) and / or a media output ( 20 . 22 ) is trained. Redox fuel cell system according to claim 3, characterized in that the regenerator stack ( 6 ) and the fuel cell stack ( 16 ) are arranged side by side, wherein in at least one of the end plates ( 17 . 18 ) a cavity is formed through which a medium exchange, preferably the catholyte solution (L), between regenerator stack ( 6 ) and fuel cell stacks ( 16 ), whereby this media exchange is completely carried out in the respective end plate ( 17 . 18 ) and not outside the end plate ( 17 . 18 ) he follows. Redox fuel cell system according to one of Claims 1 to 3, characterized by a middle plate ( 19 ) between the fuel cell stack ( 16 ) and the regenerator stack ( 6 ). Redox fuel cell system according to claim 5, characterized in that through cavities in the middle plate ( 19 ) a medium exchange, preferably the catholyte solution (L), between regenerator stack ( 6 ) and fuel cell stacks ( 16 ) is possible. Redox fuel cell system according to one of claims 3 to 6, characterized in that in at least one of the two end plates ( 17 . 18 ) or in the middle plate ( 19 ) a pumping device ( 8th ), preferably for the catholyte solution or a cooling circuit is integrated. Redox fuel cell system according to one of claims 3 to 7, characterized in that in the second end plate ( 18 ) and / or the middle plate ( 19 ) A Regeneratorbypassventil is arranged, via the Regeneratorbypassventil catholyte solution is derivable into a reservoir. Redox fuel cell systems according to claim 8, characterized in that the reservoir in the middle plate ( 19 ) is trained. Method for producing a redox fuel cell system ( 1 ), comprising the following steps: • stacking at least one redox fuel cell ( 13 ) to a fuel cell stack ( 16 ), wherein the redox fuel cell ( 13 ) an anode ( 2 ) and a cathode ( 3 ) separated by an ion-selective separator ( 4 ) are separated, wherein the fuel cell stack ( 16 ) is configured for passing a fuel and a catholyte solution (L), and • stacking a plurality of regenerator plates ( 14 ) to a regenerator stack ( 6 ), wherein the regenerator stack ( 6 ) is designed for the regeneration of the catholyte solution (L), and wherein the regenerator stack ( 6 ) is designed for passing through the catholyte solution (L) and an oxidizing fluid, wherein the fuel cell stack ( 16 ) and the regenerator stack ( 6 ) are arranged one above the other or next to each other and via a common bracing system ( 15 ).

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