DE102014221148A1 - Operating method of a redox flow system and a motor vehicle and redox flow system and motor vehicle with a redox flow system - Google Patents

Abstract

Redox flow system 10 and motor vehicle comprising: 1) at least one redox flow cell 100 having an anode 120 and a cathode 130 separated by an ion selective separator 140; 2) at least one active material store 210, 310 for storing a redox active material AM, the active material store 210, 310 providing active material AM for the anode 120 or for the cathode 130; 3) at least one solvent addition unit 220, 320 disposed upstream of the anode 120 or the cathode 130, wherein the solvent addition unit 220, 320 is adapted to add solvent L to the redox active material AM; 4) at least one solvent removal unit 240, 340 located downstream of the anode 120 or the cathode 130, the solvent removal unit 240, 340 being adapted to remove solvent L; and 5) at least one recycle 270, 370 adapted to supply the removed solvent L to the solvent addition unit 220, 320. Also disclosed is a method for operating a redox flow system or a motor vehicle.

Description

The technology disclosed herein relates to an operating method of a redox flow system and a motor vehicle as well as a redox flow system and a motor vehicle with a redox flow system.

The technology disclosed herein relates to a redox flow system having at least one redox flow cell. A redox flow cell comprises an anode and a cathode separated by an ion permeable separator. Such redox flow cells are known per se. They are used, for example, in redox flow batteries. In a redox flow battery or redox flow battery, the redox flow cell or redox flow cell is flowed through by two energy-storing electrolyte solutions which contain active materials or redox pairs in an ionic form. The electrolyte solutions are stored in external tanks. The electrolyte in the cathode fluid circuit is referred to as catholyte, the electrolyte of the anode fluid circuit as anolyte. In addition to batteries with electrolyte tanks for the catholyte solution and anolyte solution, structures are also known in which vanadium is used as the anolyte solution and the cathode is traversed by atmospheric oxygen. On the cathode side, the energy converter is thus supplied with oxygen, whereby the catholyte solution can be omitted. Redox flow cells are also used in some redox flow fuel cell systems.

A disadvantage of such redox flow systems is that the electrolyte solutions used hitherto have a relatively low energy storage capacity. The active materials are present in previously known electrolytes mainly in dissolved form (electrolyte solution). The amount of active materials of the prior art electrolytes is therefore limited by the solubility limit. As a result, only an energy density can be achieved at a reasonable cost, which makes the use for mobile applications not competitive.

An "electrolyte" is generally a chemical compound that is dissociated into ions in the solid, liquid or dissolved state. "Electrolyte" is also the solid or liquid material that contains the mobile ions.

For example, is from the US 2010047671 A a redox flow system known in which semisolid or solid particles are transported to the redox flow cell, so that there the stored energy is converted. In comparison with semisolid or solid particles, electrolytes with dissolved active materials can be transported through the fuel cell system comparatively easily and with little energy expenditure.

It is an object of the present invention to reduce or eliminate the disadvantages of the previously known solution. In particular, it is an object of the technology disclosed herein to provide a redox flow system for mobile applications, which can provide energy for long journeys of a vehicle at preferably low dead weight.

The object (s) is / are solved by the subject matter of the independent claims. The dependent claims represent preferred embodiments.

The technology disclosed herein relates to a redox flow system having at least one redox flow cell. A redox flow cell comprises an anode and a cathode. The anode and cathode are separated by an ion selective separator.

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 ^®. For simplicity's sake, a system with a redox flow cell is often discussed here. If a component of the system is listed below in the singular, the majority should also be included. For example, a plurality of redox flow cells and partially a plurality of system components may be provided.

The redox flow system comprises at least one active material store for storing a redox active material. The redox-active material (hereinafter: active material) is the redox couple which reacts in the redox-flow cell and is responsible for the generation of cell voltage.

For the redox flow system disclosed here, in principle all active materials are considered which are both oxidized and reduced in the liquid phase. Particularly interesting are pairings with the highest possible or low reference potential, a low formula weight and the ability to exchange several electrons per formula turnover. Active materials are preferably used which dissolve well in the solvent, preferably water. Such active materials are known in the art. For example, a redox flow battery system is conceivable in which vanadium is used as the active material in the anolyte and in the catholyte. Other redox flow systems work, for example, with vanadium and chromium, with zinc and bromine or with vanadium and oxygen.

For example, be provided as active material vanadium. The active material storage provides the active material for the anode or for the cathode. The at least one active material store may be connected to the anode or to the cathode (fluid). Preferably, two reservoirs are provided, one reservoir storing the active material for the catholyte and one reservoir storing the active material for the anolyte.

The redox flow system further comprises at least one solvent addition unit located upstream of the redox flow cell or anode or cathode.

The solvent addition unit is suitable for adding solvent to the active material. Such a solvent addition unit may, for example, be designed as a mixer to which the active material is fed via a screw conveyor or via a conveyor belt.

The solvent addition unit is configured such that a measurable volume of solvent from the solvent tank is placed in a mixing vessel and a measured amount of active material, in powder, paste or liquid form, is added to adjust a preferably homogeneous concentration. The mixing unit is preferably designed as a magnetic mixer. So a closed container can be used and leakage problems are avoided.

For example, the solvent can be applied as a spray on powdered active material, for. B. in a mixer.

Preferably, the solvent addition unit is located downstream or in the active material storage. The at least one solvent addition unit may be formed integrally with the active material storage. The term "downstream" refers to the flow of the active material.

The redox flow system further comprises at least one solvent removal unit. The solvent removal unit is located downstream of the redox flow cell or anode or cathode. The solvent removal unit is suitable for removing or separating the solvent, in particular from an electrolyte solution.

The redox flow system further comprises at least one recycle capable of feeding the solvent removed from the electrolyte to the solvent addition unit. The recycle may provide the removed solvent for re-addition to the active material upstream of the redox flow cell or anode or cathode.

For example, the recycle may include a tubing member connecting the solvent removal unit to the solvent addition unit. Further, the recycle may include a tank for (intermediate) storage of solvent. In a further embodiment, the solvent addition unit, the solvent removal unit and / or the tank for storing the solvent are housed in a housing.

The technology disclosed herein further includes an operating method for a redox flow system. The operating method preferably comprises the step of storing at least one active material (AM) in at least one active material store, the active material store providing active material for an anode or for a cathode of at least one redox flow cell of the redox flow system.

The operating method for a redox flow system comprises the step of adding solvent to the active material, especially in a solvent addition unit upstream of the anode or the cathode, and preferably downstream or in the active material storage.

Furthermore, the operating method comprises the step: solvent removal downstream of the redox flow cell or the anode or the cathode, in particular in a solvent removal unit. In this case, at least a part of the solvent is removed again.

Further, the operating method comprises the step of providing the removed solvent for re-addition to the active material upstream of the redox flow cell or anode or cathode, in particular by recycling the removed solvent to the solvent addition unit.

The solvent addition unit and / or the solvent removal unit may be functionally integrated in other components of the redox flow system and structurally need not be a separate unit.

The technology disclosed here relates in particular to a system and a method in which the active material, in particular in an active material storage, can be stored or stored as dry powder, paste, pellets and / or highly concentrated solution. Particularly preferably, the active material is stored as a highly concentrated solution having a concentration of at least 3 molar, more preferably of 17 molar, and particularly preferably of 30 molar.

Preferably, the active material may be solubilized in the solvent addition unit. The resulting electrolyte solution comprising the solvent and the active material may then be supplied to the at least one redox flow cell. The active materials are preferably brought into solution only for passage through the cell stack or stack or energy converter having the at least one redox flow cell. In other words, the dry or almost dry active material is placed in solution in front of the stack and after the stack the solvent is completely or largely removed. The withdrawn solvent is then passed to a location in front of the stack where it is reused to solubilize the dry active material. Thus, therefore, there is a closed solvent cycle in which the solvent can be recycled continuously. This process can be used on both the cathode side and the anode side. Alternatively, it is possible to obtain a suspension by adding solvent, which can then be fed to the at least one redox flow cell.

Compared to the previously known solutions, a comparatively small volume of solvent is required for the transport of the dissolved active materials through the stack. Since most of the solvent is in the solvent cycle and the active materials are stored in semisolid or solid form or as a highly concentrated solution, much of the solvent can be saved over conventional redox flow systems with an electrolyte storage device. For mobile applications, such as. A motor vehicle, thus up to 200 to 300 liters of solvent could be saved, which can lead to a significant reduction in weight of the overall system. Due to the reduced vehicle weight, moreover, improved longitudinal and lateral dynamics and increased safety can be achieved. Moreover, the system disclosed here has savings potential with regard to the installation space. With the system disclosed here, it is possible to realize motor vehicles which can already cover series-ready ranges with a storage charge without thereby increasing the total weight of the motor vehicle to a non-series-capable total weight.

Preferably, the redox flow system comprises two active material reservoirs, two solvent addition units and two solvent removal units. Preferably, an active material storage, a solvent addition unit, and a solvent removal unit in the anode fluid circuit and an active material storage, a solvent addition unit, and a solvent removal unit are respectively provided in the cathode fluid circuit.

In other words, the redox-flow system preferably comprises an active material storage which stores the active material for forming the catholyte. The active material for forming the catholyte is dissolved in the solvent addition unit by the addition of solvent, thereby forming the catholyte. The catholyte flows through the cathode and is subsequently reduced in the solvent removal unit of the cathode fluid circuit. Likewise, the anode fluid circuit comprises an active material storage for storing active material, which together with the solvent forms the anolyte, which finally flows through the anode before the solvent is removed in the solvent removal unit of the anode fluid circuit.

The redox-flow system may further comprise at least one residual storage tank configured to store the reacted active material after the reaction in the redox flow cell and after the solvent removal. In other words, the residual storage tank is configured to store the active material extracted from the electrolyte solution and stored. The spent active material may, for example, again be present as a highly concentrated solution or in semisolid or solid form. In one embodiment, the residual storage container and the active material storage can be accommodated in a storage housing or in a storage volume, for example, separated by a partition wall. In a further embodiment, the reacted active material is returned to the active material storage.

The redox flow system is preferably operated continuously or in stratified mode. If the redox flow system is designed, for example, as a redox flow battery, then, for example, the reacted active material can be stored in the at least one active material store. When recharging the battery then the reacted active material is again converted into usable or convertible active material. In stratified operation, for example, the completely discharged or reacted active material can be collected in the residual storage tank.

The technology disclosed herein further includes a motor vehicle having a redox flow system disclosed herein. However, the disclosed technology is not limited to mobile applications. The technology disclosed here can also be used, for example, for stationary redox flow systems for the storage of energy.

• – Verdampfung oder Verdunsten des Lösungsmittels, insbesondere unter Unterdruck;
• – Ausfällung des umgewandelten Aktivmaterials aus der umgewandelten Elektrolytlösung;
• – Umkehrosmose mittels einer semipermeablen Membran;
• – Zentrifugieren der umgewandelten Elektrolytlösung;
• – Lösungsmittelextraktion, beispielsweise durch Einbringen von mindestens einem zusätzlichen Lösungsmittel; und/oder
• – Filtration.

The removal of the solvent from the electrolyte solution converted in the at least one redox flow cell may comprise, for example, one or more of the following processes:

• - evaporation or evaporation of the solvent, in particular under reduced pressure;
• Precipitation of the converted active material from the converted electrolyte solution;
• - reverse osmosis by means of a semipermeable membrane;
• - centrifuging the converted electrolyte solution;
• - Solvent extraction, for example by introducing at least one additional solvent; and or
• - Filtration.

For example, by mechanical separation (eg, by a membrane filter or a centrifuge), the undissolved active materials can be separated from the electrolyte. In a further step, the solution can then be broken down into the constituents solvent and active material, for example by fractional distillation and / or by reverse osmosis. The necessary heat of evaporation for the distillation can, for. B. be made available from the released during the subsequent condensation heat (principle heat pump).

For example, the solvent may be provided with a precipitation additive so that the solubility of the active material is exceeded and precipitation of the active material occurs. The precipitated active material is separated mechanically (eg by a filter or a centrifuge). The solvent mixture (solvent + additive) may, for. B. be separated by fractional distillation. Alternatively, the solvent mixture can be broken down into the constituents, for example by reverse osmosis. If a precipitation additive is used, then an additional tank for storing the precipitation additive can be provided.

• – Betreiben des hier offenbarten Redox-Flow-Systems, und
• – Zuführen von Rekuperationsenergie zu der Lösungsmittelentfernungseinheit.

The technology disclosed herein further relates to an operating method of a motor vehicle, comprising the steps of:

• Operating the redox-flow system disclosed herein, and
• Supplying recuperation energy to the solvent removal unit.

Under recuperation energy is generally understood the recovered during operation of a motor vehicle energy, eg. The energy that is recovered during braking by the use of an electric motor, which is thus used as a generator for braking.

Alternatively or additionally, the recuperation energy can be used to charge a battery, preferably a redox flow battery.

In the following, the technology disclosed here will now be explained with reference to figures. Show it

1 a schematic representation of the redox flow system 10 , and

2 a schematic view of another redox flow system 10 ,

1 schematically shows the redox flow system 10 with a redox flow cell 100 and the anode fluid circuit 200 and the cathode fluid circuit 300 , The example shown here may, for example, a redox flow battery 10 be as active material AM vanadium in the anode fluid circuit 200 as well as in the cathode fluid circuit 300 used.

Come as active materials AM or as a redox pair of oxygen and vanadium used, so would the Katholytfluidstromkreis 300 omitted. Instead of the catholyte fluid circuit 300 Such a redox flow battery would be a cathode 130 have, which would be traversed by atmospheric oxygen. Such a system could then also be called a fuel cell.

The redox flow system shown here 10 includes a redox flow cell 100 with an anode 120 and a cathode 130 passing through the ion-selective separator 150 are separated from each other. The structure of the redox flow cell 100 is known from previously known redox flow batteries and will not be discussed further here. The anode fluid circuit 200 and the cathode fluid circuit 300 are the same. In both fluid circuits 200 . 300 is in each case an active material store 210 . 310 arranged, respectively with the corresponding areas of the anode 120 and the cathode 130 connected is.

The solvent addition units 220 . 320 may preferably immediately adjacent to the respective active material storage 210 . 310 be arranged. In a further embodiment, the solvent addition units 220 . 320 in the active material storage 210 . 310 or be formed integrally with these. The solvent addition unit 220 . 320 can, for example, a mixing device 220 . 320 be supplied by means of a mechanical conveyor, such as, for example, a screw conveyor, in semi-solid or solid form of active material. Furthermore, it is also conceivable that the active material is present as a highly concentrated solution, the other suitable means for mixing 220 . 320 can be transported.

It is also possible to use the solvent addition unit 220 . 320 spaced from the active material storage 210 . 310 provided. In the embodiment shown here, the solvent addition unit is 220 . 320 upstream of the redox flow cell 100 arranged. From the solvent addition units 220 . 320 flows through the mixing or in-solution bring resulting electrolyte AML, so the anolyte and the catholyte, through appropriate supply lines 230 . 330 to the redox flow cell 100 , The electrolyte AML can, for example, by means of feed pumps 260 . 360 to get promoted. In the redox flow cell 100 Then the electrochemical reactions, which are the cause of the cell voltage, take place in the system 10 ultimately can be removed. The converted in the electrochemical reaction electrolyte AM'L leaves the redox flow cell 100 and flows through appropriate derivatives 250 . 350 to the solvent removal units 240 . 340 downstream of the redox flow cell 100 are arranged. As the electrolyte, for example, an electrolyte solution or an electrolyte suspension can be used.

In the solvent removal units 240 . 340 the solvent L is at least partially removed from the spent electrolyte AM'L. The reacted electrolyte AM'L is thereby concentrated. The reacted active material AM 'can, for example, the active material storage 210 . 310 be added again. In the active material storage 210 . 310 then unconsumed active material AM and reacted active material AM 'is stored. During the charging process, converted active material AM 'is converted back into "unconsumed" active material AM.

The solution L removed from the converted electrolyte AM'L is recovered by the recycling 270 . 370 the solvent addition units 220 . 320 fed. The returns 270 . 370 can, for example, a storage tank 272 . 372 in which solvent L is intermediately stored.

Further, in the derivatives 250 . 350 a storage tank may be arranged, in which reacted electrolyte material AM'L can be temporarily stored. The intermediately stored electrolyte material AM'L can be used, for example, in recuperation phases of the solvent removal unit 240 . 340 be supplied. The recuperation energy from the electric machine can then be used, for example, to remove the solvent, which can be energy-efficiently solvent L returned.

In the embodiment shown here are the components 210 . 220 and 240 such as 310 . 320 and 340 arranged adjacent to each other. In a further embodiment, however, these components may also be spaced apart and connected to one another by lines.

2 shows a further embodiment of a redox flow system 10 , The structure is essentially the same as that of the redox flow system 10 of the 1 ,

Notwithstanding the embodiment according to 1 In the embodiment shown here, the reacted active material AM 'is not the active material storage again 210 . 310 fed. In the embodiment illustrated here, the spent active material AM 'becomes after solvent removal in the solvent removal unit 240 . 340 in the rest storage tank 280 . 380 saved. The system shown here is not a continuous system, but a system that operates in shifts.

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

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

• US 2010047671 A [0005]

Claims (9)

Operating procedure of a redox flow system ( 10 ), comprising the steps of: - storing active material (AM) in at least one active material store ( 210 . 310 ), wherein the active material storage ( 210 . 310 ) Active material (AM) for an anode ( 120 ) or for a cathode ( 130 ) of at least one redox flow cell ( 100 ) of the redox flow system ( 10 ) provides; Addition of solvent (L) to the active material (AM) upstream of the redox flow cell ( 100 ); Solvent removal downstream of the redox flow cell ( 100 ), wherein at least a part of the solvent (L) is removed again; and - providing the removed solvent (L) for re-addition to the active material (AM) upstream of the redox flow cell ( 100 ). Process according to claim 1, wherein the active material (AM) in the active material reservoir (AM) 210 . 310 ) is stored as dry powder, paste, pellets and / or highly concentrated solution. Process according to claim 1 or 2, wherein the removal of the solvent (L) from the reaction in the redox flow cell ( 100 ) converted electrolyte solution (AM'L) comprises one or more of the following process steps: - evaporation or evaporation of the solvent (L), in particular under reduced pressure; Precipitation of the converted active material (AM ') from the converted electrolyte solution (AM'L); - reverse osmosis by means of a semipermeable membrane; - centrifuging the converted electrolyte solution (AM'L); - solvent extraction; and / or filtration. Operating method of a motor vehicle, comprising the steps of: - operating a redox flow system ( 10 ) with a method according to one of the preceding claims, and - supplying recuperation energy to a solvent removal unit ( 240 . 340 ), in which at least a part of the solvent (L) is removed again. Redox flow system ( 10 ) with: - at least one redox flow cell ( 100 ), which is an anode ( 120 ), and a cathode ( 130 ) formed by an ion-selective separator ( 140 ) are separated from each other; At least one active material store ( 210 . 310 ) for storing a redox active material (AM), wherein the active material storage ( 210 . 310 ) Active material (AM) for the anode ( 120 ) or for the cathode ( 130 ) provides; At least one solvent addition unit ( 220 . 320 ) upstream of the redox flow cell ( 100 ), wherein the solvent addition unit ( 220 . 320 ) is suitable for adding solvent (L) to the redox active material (AM); At least one solvent removal unit ( 240 . 340 ) downstream of the redox flow cell ( 100 ), wherein the solvent removal unit ( 240 . 340 ) is suitable for removing solvent (L); and - at least one return ( 270 . 370 ) which is suitable for removing the solvent (L) removed from the solvent addition unit ( 220 . 320 ). Redox flow system ( 10 ) according to claim 5, wherein the at least one active material store ( 210 . 310 ) is designed to store the active material (AM) as a dry powder, paste, pellets and / or highly concentrated solution. Redox flow system ( 10 ) according to claim 5 or 6, wherein in each case an active material store ( 210 . 310 ), a solvent addition unit ( 220 . 320 ) and a solvent removal unit ( 240 . 340 ) in the anode fluid circuit ( 200 ) and in the cathode fluid circuit ( 300 ) are provided. Redox flow system ( 10 ) according to any one of claims 5 to 7, wherein the redox flow system ( 10 ) at least one residual storage tank ( 280 . 380 ), which is formed, the reacted active material (AM ') after the reaction in redox flow cell ( 100 ) and after solvent removal. Motor vehicle with a redox flow system ( 10 ) according to one of the preceding claims 5 to 8.

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