DE102022005063A1 - Redox flow battery - Google Patents

Abstract

The invention relates to a redox flow battery (1) with at least one cell (2), characterized in that at least one lance (3-1,4- 1) for a feed of the electrolyte liquid (5,6) to the at least one cell (1) and at least one lance (3-2,4-2) for a return of the electrolyte liquid (5,6) from the at least one cell ( 2) is arranged, wherein along a direction of extension of the lances (3-1,3-2,4-1,4-2) within the tanks (3,4) in each case several in a wall of the lances (3-1,3- 2,4-1,4-2) arranged holes (10) are formed.

Description

The invention relates to a redox flow battery.

A redox flow battery, which is also referred to as a liquid battery, wet cell or as a redox flow battery, is an embodiment of an accumulator. In the future, the redox flow battery can be of great importance for the storage of electrical energy from regenerative energy sources, since it can store fluctuating energies such as solar and/or wind energy and release them again when required. A feature that characterizes the redox flow battery is that the chemical energy is not stored in a solid, as is usually the case, but in a liquid electrolyte. This is usually stored in two separate tanks and can be converted into a cell of the redox flow battery if required. In an interior of the cell are two electrodes, an anode and a cathode. A membrane, in particular an ion-conducting membrane, separates or subdivides the cell into two half-cells, with one electrode each being arranged in one of the half-cells.

A frequently used type of redox flow battery is the vanadium redox flow battery, in which both electrolytes, ie the electrolyte which flows past an anode and the electrolyte which flows past a cathode, contain vanadium compounds. When the redox flow battery is discharged, the following oxidation then takes place at the anode: V ²⁺ ↔HV ³⁺ +e ^- . The following reduction takes place at the cathode during discharging: VO ²⁺ +2H ⁺ +e ^- ↔VO ²⁺ +H ₂ O. Electrons are made available at the anode, which the cathode absorbs, causing a current to flow between the two electrodes. Due to the respective electrode reaction, a charge imbalance occurs between the two half-cells, which is why a charge exchange has to take place through the membrane. This reaction is reversible in the redox flow reaction, allowing the redox flow battery to be recharged. As a rule, such a redox flow battery does not only have one cell, but several cells are combined to form a so-called stack, which means that, for example, a multiple of the power can be achieved.

In order to achieve a maximum capacity of the redox flow battery, the aim is to convert as much of the liquid electrolyte as possible during charging and discharging.

Therefore, it is important that no dead zones can form in the tanks, in which there is electrolyte liquid that is not pumped through the cell and whose charge can therefore not be changed.

From the DE 10 2010 004 942 A1 a redox flow cell is known in which stirrers with stirring blades are provided in the tanks for storing the electrolyte liquids.

The object of the invention is to improve a redox flow battery with regard to mixing the electrolyte liquids in the tanks and avoiding dead zones in the tanks.

The object is achieved according to the invention by a redox flow battery having the features of patent claim 1 . Advantageous configurations of the invention result from the dependent claims.

In particular, a redox flow battery is created, with at least one cell, wherein at least one lance for a supply of the electrolyte liquid to the at least one cell and/or for a return of the electrolyte liquid from the at least one cell is arranged in tanks for storing electrolyte liquids, wherein in each case a plurality of holes arranged in a wall of the at least one lance are formed within the tank along a direction in which the at least one lance extends.

The redox flow battery makes it possible to remove the electrolyte liquids from the tank (flow from the tank to the cell) and/or return them (return from the cell to the tank) in such a way that a turbulent flow occurs in the tank, which leads to a mixing of the Electrolyte liquid leads throughout the tank. In this way, in particular, the formation of dead zones within the tank can be prevented, so that a charge of the entire electrolyte liquid is available for charging/discharging. This is achieved in that each tank of the redox flow battery has at least one lance for a flow and/or a return, via which the electrolyte liquid is removed or fed back again. The at least one lance is in particular elongated and hollow on the inside or designed as a hollow body and has a plurality of holes arranged in a wall of the lances along a direction of extension of the at least one lance within the tank, through which the electrolyte liquid enters the lance as it flows from the tank (also referred to as the flow lance) and through which the electrolyte liquid exits from the inside of the return lance into the tank during the return (also referred to as the return lance). Each of the tanks of the redox flow battery has at least one such lance for a flow and/or a return. In particular each of the tanks has at least one such lance for the return (return lance). The multiple holes in the wall of the at least one lance generate the turbulent flow in the tanks, which leads to efficient mixing of the respective electrolyte liquid. The turbulent flow is generated in particular by the respective exiting or entering of the electrolyte liquid through the holes, since turbulences form in the area of the individual holes due to the volume flows that occur, which propagate into the interior of the tank and thus lead to a turbulent flow in the entire tank Lead flow and effective mixing.

An advantage of the redox flow battery disclosed is that no moving parts are necessary within the tanks in order to generate mixing and in particular a turbulent flow. Furthermore, the lances are easy to manufacture and can be arranged in and attached to and/or in the tanks in a simple manner. Provision can be made, for example, for the lances to be pushed into the tanks and screwed to the respective tank. However, it is also possible to permanently weld the lances to the tanks (subsequently) or to integrate the lances into the tanks during manufacture.

The redox flow battery has at least one cell. However, it can also be provided that several cells are combined to form a stack (stack). Several cells and two tanks with the electrolyte liquids are then assigned to a stack. At least one lance is then arranged in each of the two tanks.

The holes in the walls of the lances are distributed, for example, at regular or irregular intervals over a longitudinal extension direction of the lances.

The lances are made of a suitable plastic, for example, or include such a plastic. For example, polyethylene (PE) or polypropylene (PP) can be used. In principle, polyvinyl chloride (PVC-U, PVC-C), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF) and ethylene-tetrafluoroethylene copolymer (ETFE) are also suitable due to their media resistance. The lances can have other elements for mechanical fixation and/or interface elements for connection to a pump circuit and for sealing, such as screw caps, inserts, seals, union nuts, etc. It can also be provided that such individual parts are or are welded to one another or are already welded brought into the production of the respective tank and firmly connected to it.

In one embodiment it is provided that at least one lance for feeding the electrolyte liquid to the at least one cell and at least one lance for returning the electrolyte liquid from the at least one cell are arranged in the tanks. As a result, the generation of the turbulent flow within the tanks and a thorough mixing of the respective electrolyte liquids can be further increased, since both the flow lance and the return lance contribute to this. In particular, the lances are arranged on opposite sides of the respective tank. As a result, a turbulent flow can be generated in an entire tank volume. If the tank has a rectangular or square cross section, it can also be provided that the lances are arranged in opposite corners (or along the corners).

In one embodiment it is provided that the lances are cylindrical. In particular, the lances comprise a hollow cylinder. As a result, standard components, in particular (standard) pipes, can be used to form the lances. To produce a lance, a tube is provided with bores for forming the holes, for example. The holes are formed in particular in a lateral surface of the hollow cylinder.

In one embodiment it is provided that the lances are closed at an end ending inside the tank. In this way it can be achieved that the electrolyte liquid only passes through the holes arranged in the lances.

In one embodiment it is provided that the lances are arranged vertically in the tank and extend at least over a large part of the height of the tank. As a result, the electrolyte liquid can be removed (supply) or fed back (return) over an entire height or an entire extension direction of the tank. In particular, this enables a turbulent flow to form over an entire tank volume.

In one embodiment it is provided that the holes are formed on opposite sides of the wall of the lances. This allows the electrolyte liquid to enter or exit on both (long) sides of the lances. This can further improve the formation of the turbulent flow.

In one embodiment it is provided that passage directions through the holes of respective lances for the flow and lances for the return of the tanks are arranged parallel to one another. As a result, the turbulent flow can be generated particularly effectively. In other words, in this embodiment, in particular, the holes of the flow lance and the return lance of a tank are arranged essentially facing each other.

In one embodiment it is provided that passage directions of at least some of the holes of respective lances of the tanks point in the direction of a tank center axis or tank center surface running parallel to the lances and are perpendicular to this. As a result, the generation of the turbulent flow and the mixing can be further improved. In particular, it can be provided that a volume flow is directed in the direction of the central axis of the tank or the central surfaces of the tank (in the case of holes on opposite sides also in the direction of an end wall of the tank) or is “sucked out” from this direction. This ensures that as many liquid particles as possible are moved and mixed in the tank. Mixing can thereby be improved, in particular when the tanks are enlarged along one longitudinal side in order to increase storage capacity. In particular, the tank center surface divides a side that is longer in relation to the dimensions of the tank into two equal parts.

In one embodiment it is provided that cross-sectional areas of the holes in the lances are selected such that a volume flow guided by the lances is distributed evenly over the holes of the respective lance or a respective volume flow through the holes is at least matched to one another. As a result, the same or at least a matched volume flow can be generated through the holes during forward and/or reverse travel over the entire length of a lance. This promotes the uniform mixing and the formation of the turbulent flow in the entire tank, in particular over the entire height of the tank. When selecting the cross-sectional areas of the holes, flow-physical aspects of hydrodynamics in particular are used in order to achieve the same volume flows at the individual holes. Empirical tests and/or simulations can be used here in order to find an optimal number of holes and/or optimal cross-sectional areas. For example, provision can be made to specify a starting value for a diameter or a cross-sectional area of a hole at one end of a lance and to determine the diameter or cross-sectional areas of the remaining holes using empirical tests and/or simulations.

In one embodiment it is provided that the cross-sectional areas of the holes in the lances are different, at least in groups or in sections.

In a further embodiment it is provided that a cross-sectional area of the holes in the lances for the forward flow in the direction of an end ending inside the tank increases at least in groups or in sections, and a cross-sectional area of the holes in the lances for the return flow in the direction of an end ending in the tank interior increases at least in groups or in sections decreases. In operational use, this means in particular that a cross-sectional area of the holes in the flow lance increases at least in groups or in sections as the immersion depth in the electrolyte liquid increases, and a cross-sectional area of the holes in the return lances decreases at least in groups or in sections as the immersion depth in the electrolyte liquid increases. This ensures that a guided volume flow is the same over the entire length of the lance or can at least be adjusted.

In one embodiment, it is provided that the holes have a circular cross-section, with the diameters of the circular holes in the forward flow lances at least in groups or in sections having a ratio to one another of 5:9:13 and the diameters of the circular holes in the return lances having a ratio to one another, at least in groups or sections 13:9:6. In the case of cylindrical lances with an inner diameter of 20 mm, circular holes in the flow lances can have the following diameters, for example: 5 mm, 9 mm, 13 mm. Correspondingly, the circular holes of the return lance can have the following diameters: 13 mm, 9 mm, 6 mm. In principle, other ratios can also be selected, provided that a volume flow through the individual holes of a lance can be adjusted as a result.

• 1 eine schematische Darstellung einer Ausführungsform der Redox-Flussbatterie;
• 2 eine schematische Darstellung eines Tanks und darin angeordneter Lanzen in einer Ausführungsform der Redox-Flussbatterie (Seitenansicht);
• 3 eine schematische Darstellung des Tanks und darin angeordneter Lanzen in der Ausführungsform der Redox-Flussbatterie (Draufsicht);
• 4a, b schematische Darstellungen einer Ausführungsform der Vorlauflanze in einer Seitenansicht und in einer perspektivischen Ansicht;
• 5a, b schematische Darstellungen einer Ausführungsform der Rücklauflanze in einer Seitenansicht und in einer perspektivischen Ansicht.

The invention is explained in more detail below on the basis of preferred exemplary embodiments with reference to the figures. Here show:

• 1 a schematic representation of an embodiment of the redox flow battery;
• 2 a schematic representation of a tank and lances arranged therein in one embodiment of the redox flow battery (side view);
• 3 a schematic representation of the tank and arranged therein lances in the embodiment of the redox flow battery (top view);
• 4a, b schematic representations of an embodiment of the flow lance in a side view and in a perspective view;
• 5a, b schematic representations of an embodiment of the return lance in a side view and in a perspective view.

The 1 shows a schematic representation of an embodiment of the redox flow battery 1. The redox flow battery 1 comprises a cell 2 and two tanks 3, 4, each with an electrolyte liquid 5, 6. Only one cell 2 is shown here, in principle the redox flow battery 1 but also include several cells 2, which are combined to form a (cell) stack. The electrolytic liquids 5, 6 are supplied to the cell 2 in two separate circuits 30, 40 by means of pumps 7, 8 and then returned to the tanks 3, 4 again. In an interior of the cell 2 are two electrodes, an anode - and a cathode +. A particularly ion-conducting membrane 9 separates or subdivides the cell 2 into two half-cells 2-1, 2-2, with an electrode +, - being arranged in each of the half-cells 2-1, 2-2. One of the tanks 3, 4 or one of the circuits 30, 40 is assigned to each half-cell 2-1, 2-2. For charging and discharging, the redox flow battery 1 is operated in a manner known per se, in particular in accordance with the manner described in the introduction to the description, so that it is not discussed in any more detail here.

In the example shown, both electrolyte liquids 5, 6 contain vanadium compounds, which can each be present in different states of charge. In principle, however, other suitable electrolytes can also be used.

In the tanks 3, 4 for storing the electrolyte liquids 5, 6 is a flow lance 3-1, 4-1 for a flow of the electrolyte liquid 5, 6 to the cell 2 and a return lance 3-2, 4-2 for a return of Electrolyte liquid 5, 6 from the cell 2 in the tank 3, 4 arranged. Along the direction in which the lances 3-1, 3-2, 4-1, 4-2 extend within the tanks 3, 4, several are arranged in a wall of the lances 3-1, 3-2, 4-1, 4-2 Holes 10 formed.

This is shown schematically in the 2 shown, which only represents a tank 3 and a circuit 30 . The holes 10 are arranged at regular intervals on the lances 3-1, 3-2. The flow lance 3-1 is connected to the pump 7, for example screwed to it via a standard interface. The pump 7 extends partially into the tank 3, so that the feed lance 3-1 is somewhat shorter than the return lance 3-2, which is connected, in particular screwed, to an interface on an upper side 3-3 of the tank 3.

In the embodiment of the redox flow battery 1 shown, two lances 3 - 1 , 3 - 2 , 4 - 1 , 4 - 2 are provided per tank 3 , 4 . Basically, however, the use of only one lance 3-1, 3-2, 4-1, 4-2 or more lances per tank 3.4 is possible. In particular, one return lance 3-2, 4-2 per tank 3, 4 can be provided as a single lance per tank.

In particular, it is provided that the lances 3-1, 3-2 are cylindrical. In particular, the lances 3-1, 3-2 each form a hollow cylinder or are designed in the manner of a hollow cylinder. The lances 3-1, 3-2 can, for example, comprise a (plastic) tube as an essential component, in which bores for forming the holes 10 are introduced, for example.

In particular, it is provided that the lances 3-1, 3-2 are closed at an end 11 ending inside the tank. For example, a suitable (plastic) stopper can be used for this purpose.

In particular, it is provided that the lances 3 - 1 , 3 - 2 are arranged vertically in the tank 3 and extend at least over a large part of a height 3 - 4 of the tank 3 .

In the example shown, the flow lance 3 - 1 has, in particular, eight holes 10 . In the example shown, the return lance 3-2 has, in particular, ten holes. Depending on the size of the tank 3 and/or requirements for a volume flow and/or an available pump capacity of the pump 7, more or fewer holes 10 can also be provided.

The respective holes 10 of the two lances 3-1, 3-2 are arranged on opposite sides of the lances 3-1, 3-2. In particular, it is provided that passage directions through the holes 10 of the lance 3-1 for the forward flow and the lance 3-2 for the return flow are arranged parallel to one another. In particular, a part of the holes 10 in the lances 3-1, 3-2 each point towards a nearest end wall 3-5 of the tank 3 and another part of the holes 10 in a direction parallel to the lances 3-1, 3-2 Tank center surface 3-7, which divides a longitudinal direction (length) of the tank 3 into two equal parts. The passage directions of the holes 10 are schematic table in the 3 clarifies which shows a schematic representation of a top view of the tank 3 . The passage directions of the holes are in particular perpendicular to the end wall 3-5 and/or the central area 3-7 of the tank. Directions of the volume flows caused by the holes 10 during suction and inflow are indicated schematically by arrows. The other tank 4 ( 1 ) and the other lances 4-1, 4-2 are designed in the same way.

It can be provided that cross-sectional areas of the holes 10 in the lances 3-1, 3-2 (and the lances 4-1, 4-2 of the other tank 4, 1 ) are selected in such a way that a volume flow conveyed by the lances 3-1, 3-2 is distributed evenly over the holes 10 of the respective lance 3-1, 3-2 or a respective volume flow through the holes 10 is at least matched to one another.

In particular, it can be provided for this purpose that the cross-sectional areas of the holes 10 in the lances 3-1, 3-2 are different, at least in groups or in sections.

The 4a , 4b , 5a and 5b show schematic representations of embodiments of the forward lances 3-1, 4-1 and the return lances 3-2, 4-2, each in a side view and in a perspective view. In these embodiments, the lances 3-1, 3-2, 4-1, 4-2 essentially comprise a (plastic) tube. The tube is closed at an end 11 ending inside the tank, for example by means of a (plastic) stopper. Interface elements 3-6, 4-6 are arranged at the other end 12 in order to connect the lances 3-1, 3-2, 4-1, 4-2 to the respective circuits and to fix them to the tank.

In order to generate a balanced volume flow through all the holes 10, this embodiment provides that a cross-sectional area of the holes 10 of the feed lances 3-1, 4-1 increases at least in groups or in sections in the direction of an end 11 ending in the tank interior (cf. 4a ) and a cross-sectional area of the holes 10 of the return lances 3-2, 4-2 decreases at least in groups or sections in the direction of an end 11 ending inside the tank (cf. 5a ).

In particular, this embodiment provides that the holes 10 have a circular cross section, with the diameters of the circular holes 10 of the feed lances 3-1, 4-1 at least in groups or sections having a ratio to one another of 5:9:13 and the diameters of the circular holes 10 of the return lances 3-2, 4-2 have a ratio of 13:9:6 to one another, at least in groups or in sections. In principle, however, other suitable conditions can also be provided.

With an inner diameter of the flow lances 3-1, 4-1 of 20 mm, for example, the following numbers and diameters for circular holes 10 can be provided in the direction of the end 11 ending inside the tank: four holes 10 at a distance of 135 mm each with a diameter of 5 mm, two equally spaced holes 10 with a diameter of 9 mm and two equally spaced holes 10 with a diameter of 13 mm. The forward lances 3-1, 4-1 then have a total length between the interface elements 3-6, 4-6 at the ends 12 and the ends 11 of about 950 mm. In principle, the holes 10 can also have other shapes with the same cross-sectional areas; However, circular holes 10 offer advantages in production, since they can be produced using bores.

With an inner diameter of the return lances 3-2, 4-2 of 20 mm, for example, the following numbers and diameters for circular holes 10 can be provided in the direction of the end 11 ending inside the tank: three holes 10 at a distance of 135 mm each with a 13mm diameter, three equally spaced holes 10 of 9mm diameter and four equally spaced holes 10 of 13mm diameter. The return lances 3-2, 4-2 then have a total length between interface elements 3-6, 4-6 and the ends 11 of about 1300 mm. In principle, the holes 10 can also have other shapes with the same cross-sectional areas; However, circular holes 10 offer advantages in production, since they can be produced using bores.

The specified dimensions of the lances 3-1, 3-2, 4-1, 4-2 and holes 10 as well as a number of the holes 10 are only given as examples and can be used in other embodiments, in particular with other sizes and/or shapes of the tanks, be designed differently.

Reference List

1

Redox flow battery

2

cell

2-1

half cell

2-2

half cell

3

tank

3-1

flow lance

3-2

return lance

3-3

top (of the tank)

3-4

height (of the tank)

3-5

bulkhead (of the tank)

3-6

interface element

3-7

tank center area

4

tank

4-1

flow lance

4-2

return lance

4-6

interface element

5

electrolyte fluid

6

electrolyte fluid

7

pump

8th

pump

9

membrane

10

Hole

11

end (inside the tank)

12

End

30

cycle

40

cycle

+

electrode

-

electrode

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102010004942 A1 [0006]

Claims (10)

Redox flow battery (1), with at least one cell (2), characterized in that in tanks (3,4) for storing electrolyte liquids (5,6) each having at least one lance (3-1,4-1) for one Flow of the electrolyte liquid (5,6) to the at least one cell (1) and at least one lance (3-2,4-2) for a return of the electrolyte liquid (5,6) from the at least one cell (2). , wherein along a direction of extension of the lances (3-1,3-2,4-1,4-2) within the tanks (3,4) in each case several in a wall of the lances (3-1,3-2,4- 1.4-2) arranged holes (10) are formed. Redox flow battery (1) after claim 1 , characterized in that the lances (3-1,3-2,4-1,4-2) are cylindrical. Redox flow battery (1) according to one of the preceding claims, characterized in that the lances (3-1,3-2,4-1,4-2) are closed at an end (11) ending inside the tank. Redox flow battery (1) according to any one of the preceding claims, characterized in that the lances (3-1,3-2,4-1,4-2) are arranged vertically in the tank (3,4) and at least one Most of a height (3-4) of the tanks (3.4) extend. Redox flow battery (1) according to one of the preceding claims, characterized in that the holes (10) are formed on opposite sides of the wall of the lances (3-1,3-2,4-1,4-2). Redox flow battery (1) according to any one of the preceding claims, characterized in that passage directions through the holes (10) of respective lances (3-1,4-1) for the flow and lances (3-2,4-2) for the Return of the tanks (3.4) are arranged parallel to each other. Redox flow battery (1) according to one of the preceding claims, characterized in that passage directions of at least some of the holes (10) of respective lances (3-1,3-2,4-1,4-2) of the tanks (3,4 ) point in the direction of a tank center axis or tank center surface running parallel to the lances (3-1,3-2,4-1,4-2) and are perpendicular to this. Redox flow battery (1) according to one of the preceding claims, characterized in that the cross-sectional areas of the holes (10) in the lances (3,4) are selected such that a volume flow guided by the lances (3,4) is uniform divides the holes (10) of the respective lance (3,4) or a respective volume flow through the holes is at least matched to one another. Redox flow battery (1) according to one of the preceding claims, characterized in that the cross-sectional areas of the holes (10) in the lances (3-1,3-2,4-1,4-2) are different, at least in groups or in sections. Redox flow battery (1) according to one of the preceding claims, characterized in that a cross-sectional area of the holes (10) of the lances (3-1,4-1) for the flow in the direction of an end (11) ending in the tank interior at least in groups or increases in sections and a cross-sectional area of the holes (10) of the lances (3-2,4-2) for the return flow in the direction of an end (11) ending inside the tank decreases at least in groups or in sections.

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