Stack rack for a redox flow battery
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- CELLCUBE ENERGY STORAGE GMBH
- Filing Date
- 2026-01-23
- Publication Date
- 2026-07-30
Smart Images
Figure EP2026051703_30072026_PF_FP_ABST
Abstract
Description
[0001] Stacking shelf for a redox flow battery
[0002] The present invention relates to a stack rack for a redox flow battery, which includes at least storage tanks for storing electrically differently charged electrolytes, a plurality of cell stacks, each of which comprises a plurality of electrochemical individual cells consisting of a positive half-cell and a negative half-cell, and a fluid distribution system comprising electrolyte pumps and piping for fluid distribution, by which the electrolytes can be circulated through the cell stacks. The stack rack includes a frame on which at least the cell stacks and the electrolyte pumps of the fluid distribution system of the redox flow battery can be arranged. The invention further relates to a redox flow battery comprising such a stack rack.
[0003] State of the art
[0004] A redox flow battery is a well-known electrochemical energy storage device and typically consists of storage tanks for electrolyte fluids or electrolytes with different electrical charges, such as positive and negative charges, and a fluid distribution system that circulates the electrolytes through one or more cell stacks. This fluid distribution system includes at least electrolyte pumps or pumps, as well as piping or lines to supply the electrolytes to the cell stacks from the storage tanks and return them to the storage tanks. A cell stack typically comprises several electrochemical cells, each consisting of a positive half-cell and a negative half-cell.The positive and negative half-cells of a single cell are arranged side by side and separated by a semipermeable membrane, typically an ion exchange membrane. The semipermeable membrane can be, for example, a cation and / or anion exchange membrane, e.g., based on a sulfonated fluoropolymer such as polytetrafluoroethylene (PTFE) or Nation®.
[0005] The positive half-cell contains a positive electrode within a frame, through which the positive electrolyte flows. The negative half-cell contains a negative electrode within a frame, through which the negative electrolyte flows. The positive and negative electrolytes are typically stored in separate tanks and circulated separately through the half-cells. The positive and negative electrodes are usually made of porous graphite felts, allowing the respective electrolyte to flow through them. The frames of the half-cells are arranged side by side, and the resulting individual cells are connected to form a cell stack, alternating between negative and positive half-cells.Electrically conductive electrode plates, such as bipolar plates, are arranged between individual adjacent cells of the cell stack to act as current collectors. These plates are usually made of a composite material of carbon and plastic. Current collectors are located on the axial outer surfaces of the outermost cells of the cell stack. These collectors provide an external electrical contact, allowing an electrical voltage to be drawn across the entire cell stack (discharging the redox flow battery) or applied to the cell stack (charging the redox flow battery). The cell stack is terminated on each axial outer surface by an end plate, which holds the cell stack together.
[0006] The electrolyte of a redox flow battery is a liquid and essentially comprises an electrochemical redox couple consisting of a first redox element and a second redox element, each in the form of a redox-active element or ion, or combinations of redox-active elements and / or ions with different electrical charges (oxidation states). A multitude of redox-active elements or ions, or combinations thereof, can be used as redox couples in a redox flow battery. The redox elements of a redox couple are typically dissolved in the electrolyte liquid. The electrolyte liquid is usually an aqueous acid, such as aqueous sulfuric acid. Redox flow batteries with a wide variety of redox couple combinations are known. Some non-exhaustive examples of known combinations of redox couples are: 2+ / V 3+ vs. VO2+ / VO2 + (in a vanadium redox flow battery), V 2+ / V 3+ vs. Br / CIBr2, Br2 / Br vs. S / S 2 ; Br / Br2vs. Zn 2+ / Zn, Ce 4+ / Ce 3+ vs. V 2+ / V 3+ , Fe 3+ / Fe 2+ vs. Br2 / Br, Fe 3+ / Fe 2+ vs. Cr 3+ / Cr 2+ , Mn 2+ / Mn 3+ vs. Br2 / Br, Fe 3+ / Fe 2+ vs. Ti 2+ / TiO 2+ and others. The redox elements can be contained in the electrolyte in different chemical compounds, for example in the form of sulfates, such as vanadium sulfate, or chlorides, such as vanadium chloride, with vanadium-based redox flow batteries being the most widespread.
[0007] In a vanadium-based redox flow battery, for example, the positive electrolyte fluid consists of a redox couple in the form of a vanadium species with an oxidation number of +4 (also known as V).lv or V 4+ (designated) and a vanadium species with an oxidation number of +5 (also known as V) v or V 5+ (designated as V⁻¹), whereby during charging the vanadium species with oxidation number +4 is oxidized to the electrochemically active vanadium species with oxidation number +5. The negative electrolyte liquid consists of a redox couple in the form of a vanadium species with oxidation number +2 (also designated as V⁻¹ or V⁻¹). 2+ (designated) and from a vanadium species with an oxidation number of +3 (also known as V) IH or V 3+ (designated as ) where, during charging, the vanadium species with an oxidation state of +3 is reduced to the vanadium species with an oxidation state of +2. Thus, the negative electrolyte liquid has a more negative electrochemical potential than the positive electrolyte liquid.
[0008] When a redox flow battery is operating, electrical energy is either delivered to a load or absorbed from an energy source. In the example of a vanadium-based redox flow battery, the well-known chemical reaction (redox reaction) 2H₂ takes place. + + VÜ2 + + V 2+ VO 2+ + V 3+ + H₂O is released during charging / discharging in a single cell of a redox flow battery. During the charging process, the reaction is triggered by an external current or voltage source, which applies an electrical voltage to a single cell (or the entire cell stack). The structure and function of a redox flow battery are well known, for example from WO 2018 / 087220 A1 or WO 2014 / 131702 A1.
[0009] A redox flow battery typically consists of at least one, and usually several, cell stacks that are electrically connected. A cell stack is thus understood to be a group of cells consisting of several individual cells connected in series. The cell stacks can, in turn, be connected in series to form so-called cell strings, whereby, for example, several cell strings can be connected in parallel to increase the electrical power. Such connected cell strings can then form, for example, a redox flow battery or a single battery in a battery system. Single batteries can be connected in series or parallel as needed within a battery system, with each single battery having its own electrolyte tanks and its own fluid distribution system., pumps and piping - as well as its own control unit to supply the individual cells of the cell stacks of the respective individual battery with electrolytes independently of the other individual batteries of the battery system.
[0010] For the modular design of a redox flow battery or battery system, the cell stacks forming the individual battery, along with the fluid distribution system (e.g., electrolyte pumps, piping) and the associated control electronics, can be arranged in a container, as shown, for example, in US 2021 / 0351428 A1. The electrolyte storage tanks can be located in the same container or separately. The cell stacks and at least parts of the fluid distribution system (e.g., electrolyte pumps) can be arranged in a stack rack comprising at least one racking system (e.g., steel frame) to position the cell stacks within the container. Furthermore, it is important that those components of the redox battery or an individual battery within a battery system that require maintenance or replacement in the event of damage (e.g., leakage) are easily accessible.In the event of a retrofit, components can be replaced with more powerful and / or newer ones and are easily accessible. These components primarily include the cell stack and the electrolyte pumps.
[0011] For the operation of a redox flow battery, or of a single battery within a battery system, the electrolytes must be circulated through the cell stacks, specifically through the individual cells of each cell stack, in an electrolyte circuit. A fluid distribution system with pumps and piping, primarily supply and return lines, is required to transfer the electrolytes from the storage tanks to the cell stacks and vice versa. This means that the cell stacks, as well as the fluid distribution system, and especially the pumps, are in contact with the electrolytes, whose chemistry is often problematic (e.g., corrosive, toxic, etc.) and which should not be released into the environment. Therefore, for safety reasons, it is necessary that the cell stacks and the fluid distribution system, particularly the electrolyte pumps, are at least partially enclosed in a containment basin to, for example, collect any escaping electrolyte in the event of a leak.
[0012] For example, if an arrangement of cell stacks and electrolyte pumps is chosen in a stack rack where the cell stacks and electrolyte pumps are accessible from the front and can be removed together, and share a drip tray, they can be located on the same level as the electrolyte storage tanks. Such an arrangement results in the cell stacks and electrolyte pumps being positioned, at least partially, below the fluid level of the electrolytes in the storage tanks. Since the cell stacks and pumps are at least partially below the fluid level of the electrolytes, it is necessary for safety reasons to have a drip tray designed to contain any potential leaks in the area of the cell stacks and pumps.Particularly due to the siphon effect, which occurs when the cell stacks are partially submerged in the electrolyte fluid, a leak can result in very large quantities of fluid, even after the electrolyte pumps are switched off. These leaks must be collected in a suitably designed containment tray. However, this can hinder or complicate access to the cell stacks and electrolyte pumps for repair, maintenance, and / or replacement.
[0013] Description of the invention
[0014] The object of the present invention is therefore to provide a stack rack for a redox flow battery and a redox flow battery, which on the one hand ensures safety in the event of a leak and on the other hand allows cell stacks and / or the fluid distribution system, in particular the electrolyte pumps, of the redox flow battery to be accessed in a simple, cost-saving and maintenance-friendly manner in the event of damage and / or maintenance.
[0015] This problem is solved by a stackable rack for a redox flow battery and a redox flow battery according to the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.
[0016] According to the invention, the problem is solved by a stacking rack for a redox flow battery of the type described above, wherein the stacking rack comprises a rack frame on which at least cell stacks and electrolyte pumps of a fluid distribution system of the redox flow battery can be arranged. Furthermore, the stacking rack has a collection tray which is designed as an integrated component of the stacking rack and is attached to the rack frame of the stacking rack in such a way that at least some of the cell stacks and / or electrolyte pumps that can be arranged on the rack frame are enclosed or can be received by a collection volume formed by the collection tray. The collection tray is also designed such that at least one side of the collection tray can be opened to access the collection volume formed by the collection tray, and thus the cell stacks and / or electrolyte pumps that can be arranged on the rack frame or after assembly or...to make cell stacks and / or electrolyte pumps accessible during operation of the redox flow battery.
[0017] The main advantage of the stack rack proposed according to the invention is that the integrated drip tray provides a high level of safety, particularly in the event of a leak, since the cell stacks and / or electrolyte pumps are at least partially contained within a common drip tray after assembly or during operation of the redox flow battery. The drip tray integrated into the stack rack can be designed to meet specific requirements in the event of a leak, ensuring that any escaping electrolytes are safely contained. This means that the drip tray encompasses at least a lower section of the stack rack's frame, but can also enclose upper sections of the frame or extend to the full height of the stack rack.Furthermore, the stack rack according to the invention offers the advantage that the cell stacks and / or electrolyte pumps enclosed by the collection volume of the integrated collection tray remain easily accessible for maintenance and replacement even after assembly.
[0018] It is also advantageous if the spill containment tray is designed such that at least one of its openable side panels can be folded upwards or downwards. This means that at least one side panel of the spill containment tray is either folded upwards or downwards, thus providing free access to the collection volume. Alternatively, at least one of the openable side panels can also be designed as a hinged or sliding door to provide access to the collection volume. Ideally, at least one of the openable side panels is located on one of the long sides of the stacking rack. This allows, for example, cell stacks and / or electrolyte pumps of the redox flow battery, which are attached to the part of the racking system located within the spill containment volume after assembly or...are arranged in the operation of the redox flow battery, are accessible from the front and are easy to maintain and / or replace.
[0019] In a preferred embodiment of the stacking rack, the integrated spill containment tray comprises a plastic sheet and a mechanical support. The plastic sheet can be folded into a tray according to a predefined folding pattern. In its folded state, the plastic sheet is attached to the inside of the mechanical support. The outside of the mechanical support is attached to the rack frame. Thus, the plastic sheet forms the containment volume and the inside of the spill containment tray. The outside, or side panels, of the spill containment tray are formed by the mechanical support, which can consist of, for example, at least four support plates, preferably steel plates. Advantageously, the plastic sheet is made of a flexible plastic to allow it to be folded into a tray according to the predefined folding pattern.The plastic used for the tarpaulin should ideally be chemically resistant to ensure that any electrolytes leaking from the redox flow battery are safely contained and do not enter the environment. Suitable materials for the tarpaulin include polyethylene (PE), polyvinyl chloride (PVC), and similar plastics.
[0020] In an alternative embodiment, the spill containment tray can also be made of an inflexible, chemically stable material, such as a thermoset plastic. Ideally, the spill containment tray then consists of a tray unit in which at least one side panel or side wall can be opened, and which is attached to the racking system, at least in a low-lying area or in a lower area of the stacking rack.
[0021] Furthermore, it is advantageous if the racking system includes mounting rails – e.g., horizontally oriented ones – for arranging the cell stacks and / or electrolyte pumps. These mounting rails also support and stabilize the racking system's frame, which consists of vertical and horizontal supports. Additionally, shelves can be provided on the mounting rails, facilitating the placement of the cell stacks and / or electrolyte pumps, which then rest on the racking system after being positioned. Ideally, the mounting rails are equipped with fixing elements, each connected at one end to a specific mounting rail and at the other end detachably connected to a cell stack that can be positioned on the racking system's mounting rails. The fixing elements secure the cell stacks after they have been arranged.The cell stacks are held in their respective positions during assembly in the racking system, so that the cell stacks cannot move, for example, during transport of the stacking rack (e.g., for arrangement in a container or in a hall).
[0022] In a further development of the stack rack, the mounting rails for arranging the cell stacks and / or electrolyte pumps are positioned within the rack frame in such a way that the cell stacks placed on the mounting rails occupy only a portion of the rack's depth, while the remaining portion of the depth is available for accommodating the fluid distribution system of the redox flow battery. This means that, for example, a space remains between a mounting rail (or the cell stacks and / or pumps mounted on it) and the inside of the collection tray. Ideally, this remaining space allows for the space-saving and easily accessible arrangement of the fluid distribution system's piping.
[0023] Ideally, the mounting rails in the stacking rack are equipped with retaining elements for the fluid system piping. These can be attached to the mounting rails in such a way that they extend into the remaining portion of the rack depth or into the space between the mounting rail and the inside of the drip tray. Preferably, the retaining elements have semicircular recesses in which the fluid system piping – i.e., the individual lines or pipes – can be arranged parallel to each other. The recesses hold the piping in position despite thermal expansion and prevent the build-up of mechanical stress within the piping.
[0024] Furthermore, it is advantageous if recesses for a forklift are provided at a lower, ground-level end of the racking system and / or lifting eyes and / or crossbeams are provided at an upper end of the racking system, in order to be able to easily lift the stack rack including the cell stacks and / or electrolyte pumps arranged therein, as well as other components (e.g., control unit, valve unit, heat exchanger unit) of the redox flow battery into or out of a container.
[0025] The above-mentioned problem is also solved by a redox flow battery which has at least storage tanks for storing electrically differently charged electrolytes, a plurality of cell stacks, each of which has a plurality of electrochemical individual cells consisting of a positive half-cell and a negative half-cell, and a fluid distribution system with at least electrolyte pumps and piping with which the electrolytes can be circulated through the cell stacks, wherein at least the cell stacks and / or the electrolyte pumps with the piping are arranged in a stack rack according to the invention.
[0026] Ideally, the electrolyte pumps of the redox flow battery should be located in a lower section of the stack rack, with the cell stacks positioned above the pumps. Furthermore, it is advantageous to locate at least one control unit of the redox flow battery in an upper section or at the top of the stack rack. This minimizes or prevents potential damage to the control unit in the event of a leak. Additional components of the redox flow battery, such as a valve unit and / or a heat exchanger unit, can also be located in an upper section or at the top of the stack rack. Ideally, the cell stacks and / or electrolyte pumps, along with their piping to the storage tanks, should be housed in a common container.
[0027] Brief description of the characters
[0028] The present invention is explained in more detail below with reference to Figures 1 to 7, which show exemplary, schematic, and non-limiting advantageous embodiments of the invention.
[0029] Fig. 1 shows the basic operating principle of a redox flow battery;
[0030] Fig. 2 shows a redox flow battery with a cell stack;
[0031] Fig. 3 shows the structure of a cell stack of a redox flow battery;
[0032] Fig. 4 shows an exemplary setup of a redox flow battery with multiple cell stacks;
[0033] Figs. 5a and 5b show an arrangement of a redox flow battery in a stack rack according to the invention with an integrated collection tray in the closed and open states;
[0034] Figs. 6a and 6b show a configuration of a drip tray integrated into the stack shelf in the open and closed positions.
[0035] Fig. 7 shows a detailed view of the arrangement of piping for a fluid distribution system of the redox flow battery in the stack rack according to the invention. Implementation of the invention
[0036] For better understanding, the structure and function of a redox flow battery 1 are briefly explained below with reference to Figures 1 to 4. However, the invention is by no means limited to redox flow batteries 1; other batteries, in particular flow batteries, can also be arranged in a stacking rack 60 according to the invention.
[0037] Fig. 1 shows a schematic diagram of a redox flow battery 1 using a single cell 2 of a cell stack 10 to illustrate the well-known operating principle of a redox flow battery 1. For clarity and illustration, Fig. 1 shows only a single cell 2 of a cell stack 10 of a redox flow battery 1, where a cell stack 10 will typically comprise a plurality of single cells 2 arranged side by side in the cell stack 10.
[0038] A single cell 2 consists of two half-cells 2a, 2b, which form a positive reaction chamber 3a and a negative reaction chamber 3b, wherein the two half-cells 2a, 2b, or the positive reaction chamber 3a and the negative reaction chamber 3b, are separated by a semipermeable, in particular ion-selective, membrane 4. The reaction chambers 3a, 3b are formed, for example, in recesses 6a, 6b of frames 5a, 5b. A cell electrode 7a, 7b is arranged in each of the frames 5a, 5b, or in the reaction chambers 3a, 3b, or in the recesses 6a, 6b, and is in contact with the respective electrolyte 14a, 14b located in the half-cell 2a, 2b. The recesses 6a, 6b and, if applicable, the cell electrodes 7a, 7b of a single cell 2 arranged therein are permeated by electrolytes 14a, 14b with different electrical charges (positive and negative electrolyte).Each of the electrolytes 14a, 14b contains a redox couple with specific, time-varying concentrations (depending on the state of charge) of redox elements. The semipermeable, in particular ion-selective, membrane 4 can, for example, be made of sulfonate-modified polytetrafluoroethylene (PTFE), trade name Nation™, and allows ions to equalize the charge between the positive reaction chamber 3a and the negative reaction chamber 3b (or between the electrolytes 14a, 14b contained therein). Current connections 11, 12 are also provided on a cell stack 10 of a redox flow battery 1 to tap off an electrical cell stack voltage Vz applied to the cell stack 10 via a load L (discharging the redox flow battery 1) or to apply an electrical cell stack voltage Vz to the cell stack 10 (charging the redox flow battery 1).
[0039] An electrical load L can have any form. Based on the electrical voltage, current, or power requirements of the electrical load L, a cell stack 10 can be configured in a redox flow battery 1 to provide the necessary electrical voltage and / or current. Redox flow batteries 1 are often used as stationary energy storage systems, for example, as emergency power systems for industrial plants, storage systems for renewable energy (photovoltaics, wind power), and similar applications. Consequently, depending on the application, a person skilled in the art can design or select a cell stack 10, or a parallel and / or series connection of several cell stacks 10, or of cell strings 40 consisting of several cell stacks 10, and redox pairs in a redox flow battery 1.
[0040] The electrolytes 14a, 14b are stored in storage tanks 13a, 13b and are circulated from there through the cell stack 10, specifically through each half-cell 2a, 2b of a single cell 2 of the cell stack 10, by means of electrolyte pumps 9a, 9b. For this purpose, a supply line 16a, 16b and a discharge line 17a, 17b are provided for each electrolyte 14a, 14b, which are connected via electrolyte connections 22a, 22b, 23a, 23b to associated electrolyte channels 18a, 18b, 19a, 19b (see Fig. 3) in the cell stack 10. The electrolyte pumps, or pumps 9a, 9b for short, together with a piping 15 for distributing the electrolytes 14a, 14b, or for the supply line 16a, 16b and the discharge line 17a, 17b, form a minimum configuration of a fluid distribution system of the redox flow battery 1, through which the electrolytes 14a, 14b are circulated in the redox flow battery 1.
[0041] In a cell stack 10 with several adjacent individual cells 2, an electrode plate 8, such as a bipolar plate, is arranged between each pair of adjacent individual cells 2 (see Fig. 3). At the outer ends of the cell stack 10, a current connection 11, 12 can be made on the outer electrode plates 8 or on the outer half-cells 2a, 2b (or cell electrodes 7a, 7b) of the cell stack 10, which can be electrically contacted from the outside.
[0042] A typical structure of a cell stack 10 of a redox flow battery 1 is explained in more detail with reference to Fig. 2 and Fig. 3.
[0043] A cell stack 10 of a redox flow battery 1 comprises at least one single cell 2, typically a plurality of single cells 2, each of which is in turn formed from two frames 5a, 5b of half-cells 2a, 2b. A frame 5a, 5b is preferably made of a plastic, such as an elastomer, e.g., a polyolefinic thermoplastic elastomer (TPE or TPO), such as Santoprene®, or a thermoplastic vulcanize (TPV), particularly by injection molding. In the stack direction R (direction in which the single cells 2a, 2b are arranged side by side) between two frames 5a, 5b of a single cell 2, a semipermeable membrane 4, typically an ion exchange membrane (either a cation or anion exchange membrane, e.g., Nation®), is arranged in the cell stack 10.The membrane 4 separates the reaction chambers 3a, 3b, recesses 6a, 6b of the half-cells 2a, 2b of a single cell 2, the cell electrodes 7a, 7b arranged therein, and the electrolyte fluids 14a, 14b contained therein. Between two single cells 2 adjacent in the stack direction R, an electrode plate 8, e.g., a bipolar plate, is arranged in the cell stack 10. The electrode plate 8 is inserted, as shown in Fig. 3, into mutually facing recesses 32 in the frames 5a, 5b. The frames 5a, 5b have central recesses 6a, 6b extending through the stack direction R, each forming a reaction chamber 3a, 3b in which cell electrodes 7a, 7b, e.g., carbon fiber mats, are arranged.
[0044] Through the recesses 6a, 6b in the frames 5a, 5b, the electrically differently charged electrolytes 14a, 14b are pumped through the individual cells 2, whereby the cell electrode 7a, 7b of each half-cell 2a, 2b of an individual cell 2 is permeated by an electrolyte 14a, 14b with a different electrical charge. The electrolytes 14a, 14b are supplied and discharged externally via electrolyte connections 22a, 22b, 23a, 23b and are then distributed internally via an electrolyte channel system with electrolyte channels 18a, 18b, 19a, 19b provided in the frames 5a, 5b. The electrolyte connections 22a, 22b, 23a, 23b are provided, for example, on an end plate 24 of the cell stack 10, as shown in Fig. 3, whereby other arrangements of the electrolyte connections 22a, 22b, 23a, 23b, for example on an end frame 20, are also possible.
[0045] The cell stack 10 can be terminated at both axial ends in the stack direction R by an end frame 20. An electrically conductive current collector 21 is arranged in the end frame 20, for example, in a recess on one end face of the end frame 20, and is connected to an externally extending electrical current connection 11, 12. In the illustrated embodiment, the current collector 21 rests against the last electrode plate 8 of the last individual cell 2 to establish an electrical contact. However, the current collector 21 or a current connection 11, 12 could also be designed differently. Likewise, the end frame 20 could be omitted from the cell stack 10.
[0046] In the illustrated embodiment, the cell stack 10 is arranged between two rigid end plates 24 and pressed together by clamping means 25. The clamping means 25 are, for example, designed with through bolts 26, nuts 27, washers 28, and springs 29, as shown in Fig. 2. However, the cell stack 10 can also be held together in other ways; in particular, the clamping means 25 can be designed differently. The two end plates 24 can also be arranged between two pressure plates 30, which are pressed together by the clamping means 25, as shown in Fig. 2. To prevent the frames 5a, 5b from settling due to the clamping force of the clamping means 25, a spacer 31 can also be provided between the end plates 24. The present invention is not limited to a specific embodiment of a half-cell 2a, 2b, a single cell 2, a cell stack 10, or the redox flow battery 1.Likewise, the invention is not limited to a specific electrolyte 14a, 14b or to specific redox elements in the electrolytes 14a, 14b. The above descriptions of a redox flow battery 1 serve only for better understanding.
[0047] From the above description and the basic operating principle, it is also obvious that there is a positive electrolyte 14a and a negative electrolyte 14b, just as related to this there is a positive half-cell 2a and a negative half-cell 2b of a single cell 2 of a cell stack 10 and a positive electrolyte pump 9a and a negative electrolyte pump 9b.
[0048] A redox flow battery 1 can also comprise several cell stacks 10, as illustrated in Fig. 4. In the embodiment shown in Fig. 4, two cell strings 40 are provided, each cell string 40 comprising a plurality of cell stacks 10, for example, as described above. However, a redox flow battery 1 can, of course, also have only one cell string 40. The cell stacks 10 in a cell string 40 can be electrically connected in series via the current terminals 11, 12 of the cell stacks 10 (not shown in Fig. 4 for clarity). However, other electrical connections of the cell stacks 10 in a cell string 40 are also possible, such as a parallel connection or a combination of series and parallel connections. In the embodiment shown in Fig. 4, for example, the cell strings 40 are electrically connected in parallel (not shown in Fig. 4 for clarity).However, other electrical configurations of the cell strings 40 are also possible, such as a parallel connection or a combination of series and parallel connections. Such an electrical configuration of cell strings 40 can also be referred to as a single battery 41. A redox flow battery 1, especially in a modular and / or scalable design, can comprise several such single batteries 41, whereby the single batteries 41 can in turn be electrically interconnected by a series or parallel connection or a combination of a series and parallel connection. In this way, a redox flow battery 1 with the desired electrical output voltage and the desired electrical power can be realized.
[0049] Each cell stack 10 is supplied with a positive electrolyte 14a and a negative electrolyte 14b. For this purpose, a storage tank 13a is provided for the positive electrolyte 14a and a storage tank 13b for the negative electrolyte 14b. The positive electrolyte 14a is circulated by a positive electrolyte pump 9a and the negative electrolyte 14b by a negative electrolyte pump 9b. A control unit 50 is provided to control the electrolyte pumps 9a and 9b. This control unit uses corresponding control signals Sa and Sb to control the electrolyte pumps 9a and 9b in order to, for example, set a desired flow rate of the respective electrolyte 14a and 14b through at least one cell stack 10 or the plurality of cell stacks 10 of the redox flow battery 1 or the single battery 41. The control unit 50 can also record operating data of the redox flow battery 1, e.g., using suitable sensors (e.g., current and / or voltage sensors).The control unit 50 is preferably processor-based computer hardware on which at least control software for controlling the electrolyte pumps 9a, 9b and, for example, for adjusting the flow rate is installed and runs. However, the control unit 50 can also be implemented as an integrated circuit, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).
[0050] In the case of multiple individual batteries 41, a storage tank 13a for the positive electrolyte 14a and a storage tank 13b for the negative electrolyte 14b, as well as a fluid distribution system with a positive electrolyte pump 9a and a negative electrolyte pump 9b and corresponding piping 15 for fluid distribution through the cell stacks 10, can be provided for each individual battery 41. Thus, for example, the individual batteries 41 would be electrically connected to one another but would have separate electrolyte circuits. The present invention relates primarily to a redox flow battery 1 or an individual battery 41, which comprises at least one cell stack 10, but usually several cell stacks 10, which can also be connected to form at least one cell string 40. This redox flow battery 1 or individual battery 41 has its own electrolyte circuit – i.e.,, their own fluid distribution system with at least one positive and negative electrolyte pump 9a, 9b and associated piping 15 for fluid distribution in the cell stacks 10 - as well as their own control unit 50.
[0051] In a redox flow battery 1 or a single battery 41, which has several cell stacks 10, as shown by way of example in Fig. 4, at least the cell stacks 10 and the fluid system, especially the electrolyte pumps 9a, 9b and the associated piping 15 for fluid distribution into the cell stack 10, but also other components of the redox flow battery 1, such as the control unit 50, a valve unit 51 and / or a heat exchanger unit 52, can be arranged in a stack rack 60, as shown by way of example in Fig. 5a and Fig. 5b.
[0052] Fig. 5a shows the stack rack 60 according to the invention with an integrated drip tray 70, which is designed to prevent potential leakage in the area of the cell stacks 10 and / or pumps 9a, 9b arranged in the stack rack 60, in a closed state. Fig. 5b shows the stack rack 60 according to the invention with the integrated drip tray 70 in an open state.
[0053] The stack rack 60 comprises a rack frame 61, which is, for example, a steel frame, and the drip tray 70. The rack frame 61 consists, for example, of vertical supports 62 and horizontal supports 63, which connect the upper and lower ends of the vertical supports 62 to form a frame. Mounting rails 64 are attached to this frame, on which the cell stacks 10 and electrolyte pumps 9a, 9b of the redox flow battery 1 can be arranged directly or on support surfaces – as will be explained in more detail below. The drip tray 70 is designed as an integrated component of the stack rack 60. For this purpose, the drip tray 70 is attached to the rack frame 61 in such a way that at least a portion of the cell stacks 10 and / or electrolyte pumps 9a, 9b that can be arranged on the rack frame 61 are enclosed by a collection volume of the drip tray 70. This means, as shown, for example, in Fig. 5a and Fig. 62, that the drip tray 70 contains the cell stacks 10 and / or electrolyte pumps 9a, 9b that can be arranged on the rack frame 61.
[0054] As can be seen in Fig. 5b, for example, some of the cell stacks 10 arranged in the stack rack 60 or the rack frame 61 are located directly within the collection volume of the drip tray 70. If the electrolyte pumps 9a, 9b are arranged, for example, in a lower or near-bottom part of the stack rack 60 – e.g., below the cell stacks 10 – as shown by way of example in Fig. 5b, then the electrolyte pumps 9a, 9b are also located directly within the collection volume of the drip tray 70. Alternatively, the electrolyte pumps 9a, 9b can also be arranged in the stack rack 60 or the rack frame 61 (e.g., above the cell stacks 10) in such a way that they are located above the collection volume of the drip tray 70. Alternatively, the collection tray 70 can also be designed such that the collection volume formed by the collection tray 70, for example, encloses all cell stacks 10 arranged in the stack rack 60 and the electrolyte pumps 9a, 9b. The collection tray 70 would then, for example, be sized to a total height G and shelf depth T of the stack rack 60.designed for the shelf frame 61.
[0055] Furthermore, the collection tray 70 – as shown by way of example and schematically in Fig. 5b – is designed such that at least one side panel 71 of the collection tray 70 can be opened to provide access to the collection volume formed by the collection tray 70 and to a portion of the racking system 61 enclosed therein, as well as to the cell stacks 10 and / or electrolyte pumps 9a, 9b arranged therein. Ideally, the at least one side panel 71 that can be opened is located on a longitudinal side of the stacking system 60, so that the cell stacks 10 and / or electrolyte pumps 9a, 9b arranged in the racking system 61 are accessible from the front.
[0056] The spill containment tray 70 can, for example, consist of a plastic sheet 72 folded into a tray 70 according to a predefinable folding pattern. Fig. 6a shows an example of a plastic sheet 72 folded into a tray 70 with flaps 73 created by the folding pattern. The plastic sheet 72 can, for example, be made of a chemically resistant plastic such as polyethylene (PE), polyvinyl chloride (PVC), or similar material. This tray 70, folded from the plastic sheet 72, can, for example, line at least a floor-level area, typically a lower area, of the stacking rack 60 or racking frame 61. Furthermore, the spill containment tray 70 has mechanical support 74, which is formed, for example, by at least four support plates (e.g., steel plates). This mechanical support 74 can, as can be seen, for example, in Figs. 5a and 5b, be attached to the racking frame 61 with its outer surface.The outer sides of the plastic sheet 72 are mechanically supported by the mechanical support 74 and form the outer side walls or side panels 71 of the collection tray 70. The plastic sheet 72, or the tray 70 formed by the predetermined folding pattern, is detachably attached to an inner side of the mechanical support 74, i.e., to a respective inner side of the at least four support plates. For this purpose, the plastic sheet 72 can, for example, have recesses 75, which, in a folded state of the plastic sheet 72, are arranged, for example, at an upper edge of the tray (as shown, for example, in Fig. 6a). By means of these recesses 75, the plastic sheet 72, or the tray 70 folded from it, can be fixed to the mechanical support 74 and thus to the rack frame 61. That is, the folded plastic sheet 72 is, for example, secured by means of the recesses 75 at fixing points on a side of the mechanical support 74 facing the plastic sheet 72 in the assembled state.The support plates are detachably fastened, thereby forming the drip tray 70. One side of the mechanical support 74 or the support plates facing away from the plastic tarpaulin 72 can, for example, be in contact with the racking system 61 – especially with the vertical supports 62.
[0057] To provide access to the cell stacks 10 and / or electrolyte pumps 9a, 9b located in the collection volume of the collection tray 70, at least one side panel 71 of the collection tray 70 can be opened. Ideally, this is one of the side panels 71 attached to one of the longitudinal sides of the stack rack 60, so that the cell stacks 10 and / or electrolyte pumps 9a, 9b arranged in the rack 61 are accessible from the front. As shown in the exemplary illustration of a redox flow battery 1 arrangement in the stack rack 60 in Fig. 5b, the at least one side panel 71 of the collection tray 70, which is attached to one of the longitudinal sides of the stack rack 60, can be folded downwards. That is, the mechanical support 74 (e.g., one of the support plates) can be folded downwards together with the plastic sheet 72, which forms the tray 70 when folded. This could, for example,It may be necessary to at least partially release the fixation of the plastic sheet 72 to the mechanical support 74 in order to unfold the plastic sheet 72 on this side of the tub, as is shown by way of example in Fig. 6b.
[0058] Alternatively, at least one of the opening side panels 71 of the collection tray 70 can also be designed such that the associated support plate of the mechanical support 74 can be folded upwards. The opening side panel 71 can, for example, be designed as a hinged door or a sliding door. After opening the side panel 71 – i.e., after folding the associated support plate upwards or after opening the hinged or sliding door – the plastic sheet 72 must then, for example, be at least partially detached from the mechanical support 74 and unfolded (as shown in Fig. 6a) so that the cell stacks 10 and / or the electrolyte pumps 9a, 9b in the racking system, which are located in the collection volume of the collection tray 70, are accessible, for example, for maintenance and / or replacement.
[0059] In an alternative embodiment, the collection tray 70 can, for example, also be made of an inflexible, chemically stable material, such as plastic, in particular a thermoset. This material then forms the tray 70, which is attached to the racking system 61 and encloses at least a lower section of the stacking system 60. At least one side panel 71 of this tray 70 is reversible, ideally a side panel 71 located on a longitudinal side of the stacking system 60, to provide access to the cell stacks 10 and / or pumps 9a, 9b arranged in the racking system 61. This side panel 71 can also be designed to fold downwards, as shown by way of example in Fig. 5b. Alternatively, the side panel 71 could also be designed to fold upwards or as a sliding door to provide access to the cell stacks 10 and / or pumps 9a, 9b, which are arranged in the collection volume of the collection tray 70.
[0060] Furthermore, mounting rails 64 are attached to the racking system 61 of the stacking rack 60 according to the invention. The cell stacks 10 of the redox flow battery 1 or the individual battery 41 and / or the pumps 9a, 9b are primarily arranged on these rails. The cell stacks 10, as well as the electrolyte pumps 9a, 9b, can be arranged directly on the mounting rails 64, as shown, for example, in Figs. 5a and 5b. For this purpose, the mounting rails 64 can be arranged, at least in pairs, parallel and spaced apart from each other in the horizontal direction H within the racking system 61, as can be seen, such that the cell stacks 10 and / or the pumps 9a, 9b can be arranged directly on the respective parallel mounting rails 64. However, it is also possible that 64 storage surfaces are attached to the parallel mounting rails, which are held by the mounting rails 64 and on which the cell stacks 10 and / or the pumps 9a, 9b can then be arranged.The cell stacks 10 can be arranged, for example, unstacked in individual rows on the mounting rails 64 or, if present, on the support surfaces in the stack rack 60, as shown in Fig. 5a and Fig. 5b. However, it is also possible for the cell stacks 10 to be stacked on top of each other on the mounting rails 64 or the support surfaces in the stack rack 60. In this case, the cell stacks 10 can be stacked in pairs, for example, with only one cell stack 10 resting on the mounting rails 64 or the support surface, and a second cell stack 10 arranged against the first cell stack 10.
[0061] The cell stacks 10 are held in their respective positions in the stack rack 60 or on the mounting rails 64 by means of fixing elements 65. A first end of a fixing element 65 is connected to, or fixed to, the mounting rail 64 on which the cell stack 10 to be fixed is positioned directly or on a possible support surface. A second end of the fixing element 65 is detachably connected to the cell stack 10 to be fixed. This second end of the fixing element 65 can be designed, for example, to engage in a recess on the cell stack 10 to secure it. The detachable connection between the second end of the fixing element 65 and the respective cell stack 10 can also be designed, for example, as a screw connection. The fixing elements 65 hold each cell stack 10 in its position from at least two directions. That is, for example,On two parallel mounting rails 64, on which the respective cell stack 10 is mounted, at least one fixing element 65 is provided on both a first mounting rail 64 and a second mounting rail 64, by which the cell stack 10 can be held in its position in the stack shelf 60.
[0062] Furthermore, in the stacking rack 60 according to the invention, the mounting rails 64 are arranged within the frame of the racking system 61 such that the cell stacks 10 mounted on the mounting rails 64 occupy only a portion of the racking depth T of the stacking rack 60. This leaves a free space in the horizontal direction H in front of the mounting rails 64, or, in the case of cell stacks 10, in front of the cell stacks 10, which is formed by a remaining portion of the racking depth T. Ideally, this free space is located on the side of the stacking rack 60 where at least one openable side panel 71 of the integrated drip tray 70 is also located. The piping 15 for fluid distribution by the electrolyte pumps 9a, 9b in the cell stacks 10 can then be arranged, for example, in this free space or in the remaining portion of the racking depth T. If this is arranged in the area of the openable side part 71 of the collection tray 70, as shown in Fig. 5b, then the piping is also e.g.Easily accessible for maintenance and / or inspection.
[0063] To enable the piping 15 to be arranged in this free space between mounting rails 64 or cell stacks 10 and an inner side of the openable side panel 71 of the collection tray 70, retaining elements 66 are provided on the mounting rails 64 in the stack rack 60. The piping 15 for the fluid distribution of the fluid distribution system can be arranged on these retaining elements 66, running parallel to the mounting rails 64. A detailed view of the arrangement of the piping 15 on the retaining elements 66 of the stack rack 60 according to the invention is shown by way of example in Fig. 7, whereby, for the sake of clarity, only a section of the piping 15 is shown. The retaining elements 66 have recesses or cutouts 67, which are preferably semicircular in shape. The recesses or cutouts 67 space the parallel fluid tubes of the piping 15 apart from one another.This ensures that the fluid tubes of the piping 15 remain in their respective positions despite thermal expansion. Furthermore, the recesses 67 prevent the build-up of mechanical stresses in the piping 15, which could lead to potential damage to screw connections and / or welds. The retaining elements 67 are also designed to support the weight of the filled piping 15 for fluid distribution.
[0064] Furthermore, hose connections 151 can also be arranged in the free space remaining in the horizontal direction H between the mounting strips 64 or the cell stacks 10 and the inside of the openable side panel 71 of the collection tray 70. The hose connections 151 allow the individual cell stacks 10 to be connected to the piping 15 for fluid distribution in order to circulate the electrolytes 14a, 14b through the cell stacks 10. Figure 7 shows the hose connections 151 as an example for a cell stack 10. In a redox flow battery 1 or individual battery 41, all cell stacks 10 naturally have such hose connections 151 to the piping 15.
[0065] The electrolyte pumps 9a, 9b can, for example, be arranged on mounting rails 64 or on a support surface below the cell stacks 10, as shown in Fig. 5b – e.g., in a lower or near-bottom area of the stack rack 60. However, it is also conceivable that the pumps 9a, 9b are arranged on mounting rails or support surfaces above the cell stacks 10.
[0066] The piping 15, which for clarity is only partially shown in Figs. 5a and 5b, can, for example, extend to the upper end of the stack rack 60, where, for example, the control unit 50 and the heat exchanger unit 52 are located, along with the valve unit 51. The valve unit 51 has several valves with which the piping 15 is equipped, and which can, for example, perform several functions. The valve unit 51 can, for example, serve to interrupt the siphon effect. In the event of a leak, for example, the siphon effect is vented by selectively opening a corresponding valve, thus interrupting the piping and the fluid flow. Furthermore, the valve unit 51 can be used for quality control by taking electrolyte samples. Additionally, the valve unit 51 can be used—via the valve that connects the piping 15 to the storage tanks 13a, 13b of the electrolytes 14a, 14b—to selectively decouple or...A connection can be established with the storage tanks 13a, 13b. This allows for the exchange and separate transport of storage tanks 13a, 13b and the redox flow battery components arranged in the stack rack 60. Downstream of the valve unit 51, the piping 15 can be routed to the storage tanks 13a, 13b in the form of fluid lines 16a, 16b, 17a, 17b, with at least one of the lines 16a, 16b, 17a, 17b passing through the heat exchanger unit.
[0067] Furthermore, the stack rack 60 can have recesses at a lower end – e.g., in horizontal supports 63 near the ground or in a floor area (not shown in Fig. 5a and Fig. 5b). These recesses can be designed, for example, such that the stack rack 60, including the cell stacks 10, pumps 9a, 9b, piping 15, and any other components 50, 51, 52 of the redox flow battery arranged therein, can be lifted by a forklift in order to lift the stack rack 60, e.g., into or out of a container, or to transport it to an installation location in a hall. Alternatively or additionally, the stack rack 60, or the rack frame, can have lifting eyes or crossbeams at the upper end, e.g., on the horizontal supports 63 (also shown in Fig. 5a and Fig. 5b).5b not shown), in order to be able to lift the stack shelf 60 including the cell stacks 10, pumps 9a, 9b, piping 15 and other components 50, 51, 52, for example by means of a crane.
[0068] The stack shelf 60 or the arrangement of the redox flow battery 1, i.e., the cell stack 10, the fluid distribution system with the electrolyte pumps 9a, 9b and the piping 15 as well as the other components, such as control unit 50, valve unit 51 and heat exchanger unit 52, can, for example, be arranged together with the associated storage tanks 13a, 13b for the electrolytes 14a, 14b in a common container.
[0069] It is also conceivable that the stack rack 60, with the cell stacks 10, fluid distribution system, etc. arranged therein, is placed separately from the electrolyte storage tanks 13a, 13b in a container or is arranged in a hall with the electrolyte storage tanks 13a, 13b. The collection volume of the drip tray 70 of the stack rack 60 can be adapted to the respective requirements by adjusting the height of the side panels 71 of the drip tray 70 in order to provide safety in the event of a leak. Thanks to at least one openable side panel 71 of the drip tray 70 integrated into the stack rack 60, the cell stacks 10 and the electric pumps 9a, 9b are easily accessible for maintenance and / or replacement even during operation of the redox flow battery 1 or the individual battery 41 of a battery system.
Claims
Patent claims 1. Stack rack (60) for a redox flow battery (1, 41), which has at least storage tanks (13a, 13b) for storing electrically differently charged electrolytes (14a, 14b), a plurality of cell stacks (10), each of which has a plurality of electrochemical individual cells (2) consisting of a positive half-cell (2a) and a negative half-cell (2b), and a fluid distribution system which has at least electrolyte pumps (9a, 9b) and a piping system (15) and with which the electrolytes (14a, 14b) can be circulated through the cell stacks (10), wherein the stack rack (60) comprises a rack frame (61) on which at least the cell stacks (10) and the electrolyte pumps (9a, 9b) of the fluid distribution system of the redox flow battery (1) can be arranged, characterized in that the stack rack (60) has a drip tray (70) which is designed as an integrated part of the stack rack (60) and is attached to the rack frame (61) in this way,that at least part of the cell stacks (10) and / or electrolyte pumps (9a, 9b) that can be arranged on the shelf frame (61) of the stack shelf (60) are enclosed by a collection volume formed by the collection tray (70), and that the collection tray (70) is designed such that at least one side part (71) of the collection tray (70) is openable in order to make the collection volume formed by the collection tray (70) accessible.
2. Stacking rack (60) according to claim 1, characterized in that the collection tray (70) is designed such that the at least one openable side part (71) of the collection tray (71) can be folded upwards or folded downwards or is designed as a hinged door or as a sliding door to make the collection volume of the collection tray (70) accessible.
3. Stack shelf (60) according to claim 1 or 2, characterized in that the at least one openable side part (71) of the collection tray (70) is provided on one of the longitudinal sides of the stack shelf (60).
4. Stacking rack (60) according to one of claims 1 to 3, characterized in that the collection tray (70) comprises a plastic sheet (72) which is folded into a tray (70) according to a predefinable folding pattern, and a mechanical support (74) to the inside of which the plastic sheet (72) is attached in the folded state and the outside of which is attached to the rack frame.
5. Stacking rack (60) according to claim 4, characterized in that the plastic sheet (72) is made of a flexible, chemically resistant plastic.
6. Stacking rack (60) according to claim 4 or 5, characterized in that at least four support plates, preferably steel plates, are provided as mechanical support (74).
7. Stacking rack (60) according to one of claims 1 to 3, characterized in that the collection tray (70) is made of an inflexible, chemically stable material.
8. Stack rack (60) according to one of claims 1 to 7, characterized in that at least mounting strips (64) for arranging the cell stacks (10) and / or the electrolyte pumps (9a, 9b) are provided in the rack frame (61), wherein fixing elements (65) are provided which are each connected at a first end to a respective mounting strip (64), and which each have a second end which can be detachably connected to a cell stack (10) that can be arranged on the mounting strips (64) of the rack frame (61).
9. Stack shelf (60) according to claim 8, characterized in that storage surfaces are arranged on the mounting rails (64) on which the cell stacks (10) and / or electrolyte pumps (9a, 9b) can be arranged.
10. Stack rack (60) according to one of claims 1 to 9, characterized in that the mounting rails (64) for arranging the cell stacks (10) and / or the electrolyte pumps (9a, 9b) are arranged in the rack frame (61) such that cell stacks (10) that can be arranged on the mounting rails (64) occupy only a part of a shelf depth (T) of the stack rack (6), wherein the piping (15) of the fluid distribution system of the redox flow battery (1) can be arranged in a remaining free part of the shelf depth (T).
11. Stack shelf (60) according to one of claims 8 to 10, characterized in that retaining elements (66) for the piping (15) of the fluid distribution system are provided in the stack shelf (60) on the mounting strips (64).
12. Stacking rack (60) according to claim 11, characterized in that the retaining elements (66) have semicircular recesses.
13. Stacking rack (60) according to one of claims 1 to 12, characterized in that recesses for the engagement of a forklift are provided at a lower, floor-level end of the racking frame (61) and / or that lifting eyes and / or crossbeams are provided at an upper end of the racking frame (61).
14. Redox flow battery (1) comprising at least storage tanks (13a, 13b) for storing electrically differently charged electrolytes (14a, 14b), a plurality of cell stacks (10), each of which has a plurality of electrochemical single cells (2) consisting of a positive half-cell (2a) and a negative half-cell (2b), and a fluid distribution system with at least electrolyte pumps (9a, 9b) and a piping system (15) by which the electrolytes (14a, 14b) can be circulated through the cell stacks (10), wherein at least the cell stacks (10) and / or the electrolyte pumps (9a, 9b) are arranged with the piping system (15) in a stack rack (60) according to one of claims 1 to 13.
15. Redox flow battery (1) according to claim 14, wherein the electrolyte pumps (9a, 9b) of the redox flow battery (1) are arranged in a lower region of the stack shelf (6), and wherein the cell stacks (10) are arranged in the stack shelf (60) above the electrolyte pumps (9a, 9b).
16. Redox flow battery according to claim 14 or 15, wherein at least one control unit (50) of the redox flow battery is arranged in an upper region or at an upper end of the stack shelf (60).
17. Redox flow battery according to one of claims 14 to 16, wherein the cell stacks (10) and / or electrolyte pumps (9a, 9b) arranged at least in the stack rack (60) are arranged with the piping (15) with the storage tanks (13a, 13b) in a common container.